"Paranoid" (Black Sabbath)

I'm not even going to pretend that I'm a metal fan or know all that much about the band Black Sabbath.  As a music fan, I've heard the names Geezer Butler and Tony Iommi mentioned in passing for years, but I don't know enough to talk about their musical roots or playing styles, other than to use the word "heavy."  And the little I know about frontman Ozzy Osbourne (sadly) comes from The Osbournes 2000s T.V. show and the infamous, dubious lore about his stage antics.  It's still hard for me to imagine the shellshocked, soft-hearted patriarch of that reality show biting the head off any kind of bat/dove/porpoise/whatever it was he purportedly gnawed on stage.
No, my passing knowledge of the band comes from hearing their sledgehammer riffs flying at me through stadium speakers.  (Because nothing says "hit that home run" like the bludgeoning riff from "Iron Man" or "War Pigs.")
Same goes for the song at hand, "Paranoid," which comes from the 1970 album of the same name.  That riff is so chiseled in stone and full of adrenaline that it's undeniable.
Seriously, if you're not motivated to kick ass by the time Osbourne's voice erupts from the track, then you might want to go back and warm that bench.  Just saying.
I came across a 2010 interview with Butler via the Gibson guitars website (which is kind of interesting, considering Butler plays bass, but whatever), where he talked about how the track came about.  
In short, the song was an afterthought.  The album was essentially done, when their producer, Rodger Bain, told them they needed a short filler track to round things out.  Not having anything else in the bag, they came up with "Paranoid" in the studio, with Butler quickly writing some words for Osbourne to sing.  (The famously staccato manner in which Ozzy delivers the lyrics on the track is largely because he was still learning them.) 
Said Butler of the band's arguably most famous song: "Tony [Iommi] just played this riff, and we all went along with it.  We didn’t think anything of it."

"Immigrant Song" (Led Zeppelin)

That aaah-aaah-aaaaaaaah-aaah! banshee wail.  It's as jarring as it is invigorating.  
Case in point: I was sitting at a New York Rangers hockey game not too long ago.  It was second period, score still 0-0, and the Rangers were struggling to get momentum going.  To be blunt, the crowd was damn bored.  But the moment "Immigrant Song" and Robert Plant's vocal came blasting through the Madison Square Garden speakers during a T.V. timeout, you could feel the crowd perk up.  Not two seconds after puck drop, the crowd began yelling Let's go, Rangers! like their lives depended on it, and the guys on the ice finally woke up to earn their millions.
I bring this up because "Immigrant Song" was made for arenas.  In fact, it opened pretty much every one of Led Zeppelin's shows from 1970-1972.
As Plant notes in this video, the song was inspired by a gig the band played in Reykjavik in 1970.  Zep had been invited to Iceland as British cultural ambassadors and were set to play a concert arranged by the government.  Unfortunately, the band's arrival coincided with a massive strike by the nation's civil servants, so the concert was going to be scrapped.  But one of the universities in Reykjavik (Plant doesn't say which one) stepped in to save the day, calling off classes for two days so that faculty and students could prepare the city's Laugardalsholl Hall, an indoor sports venue, so that the concert could go on.  The warm welcome from the nation and outpouring of affection from these college students really struck the band, Plant in particular.
As he says in the clip, "We got off a plane, and we were given Iceland on a plate."
To capture the feeling of the Icelandic visit, Plant borrowed imagery from the small nation's Viking heritage, imagining Zep as modern day Nordic warriors coming to conquer new lands.
That said, the song is not the cock-rock manifesto for conquering the world that most people think it is; it's meant to be funny.  It's Plant and his pals making a joke about their public image as leaden metalheads.  Actually, quite a bit of Led Zeppelin III is a message to fans and the music press to "lighten up."  (Check out the tracks "Out on the Tiles," "Gallows Pole," and "Hats Off to (Roy) Harper" for further evidence.)

"Come Together" (The Beatles)

I wasn't always in love with "Come Together."  I hated it as a child, actually.  

More than anything, John Lennon's eerie, whispered Shoot me's followed by those echoey handclaps scared the hell out of me when I was little.  But there also were his lyrics: not one word seemed to be in its proper place.  It was as if he'd taken the language that my little kid brain was still trying to learn and chopped it up before also turning it inside out.  It bothered me profusely.

That's why for years when my mother would play Abbey Road (1969), I'd often ask her to start the album with George Harrison's "Something" instead of the Lennon-penned opener.

But then I hit puberty.  Half the time, my thoughts and feelings didn't make much sense, and even when they did, I wasn't all that interested in articulating them.  Suddenly, Lennon's bizarre, purposely inscrutable lyrics and twisted blues resonated with me, and all of my hormone-fueled moodiness and awkwardness—especially when it came to communication—had a theme song.

Today, I simply appreciate the song as an example of Lennon's genius and humor.  I mean, who the hell else could have gotten away with a line like Got to be good lookin', 'cause he's so hard to see?

I also feel this song is a perfect example of how this band was more than the sum of its parts.  Would the track be half as memorable without Paul McCartney's slinky bass?  Would it be half as sexy without Harrison's understated, upper-octave lead guitar?  Would it groove half as hard without Ringo Starr's thumping tom-toms and hi-hat work?

The obvious answer is "no" on all counts.

That's also the reason why no cover version of this song will ever come close to matching the rawness and animal magnetism of the original.

"Live and Let Die" (Paul McCartney & Wings)

Apart from the actual "James Bond Theme," "Live and Let Die" is the ultimate James Bond song.
It also, in my opinion, was James Paul McCartney's real return to form following the breakup of The Beatles.  (I don't count the cute-but-disposable single "Uncle Albert/Admiral Halsey."  Or, if we're talking album tracks, the highly overrated "Maybe I'm Repetitious Amazed.")  
To me, "Live and Let Die" captures both his penchant for balladry and ability to rock out like a madman when he feels so inclined.  The sentimental verses with their plaintive, cocktail lounge piano are the perfect foil for the crunch of Henry McCullough's guitar on the instrumental choruses.  And the brief bridge, which cleverly tosses in a little reggae flavor as a nod to the tropical setting of the film, provides a funky respite in the midst of the rock fire.
It is the perfect, dramatic opener for the only decent Bond film of the entire Roger Moore era.  (I mean, what the hell were they snorting when they made Moonraker?)
Story goes, ex-Beatles producer George Martin was asked to score the 1973 film Live and Let Die, so he offered the gig of writing the main theme to McCartney.  To get in composing mode, McCartney got a copy of the 1954 Ian Fleming paperback upon which the script was based, read it in an evening, and then wrote the song the next day.
In an article posted on the site of St. Louis radio station KHITS 96.3, there's a great quote from Wings drummer Denny Seiwell about how the song came together at McCartney's home studio.
"And we were up at the house one day, and he had just read the book the night before, and he sat down at the piano and said, 'James Bond...James Bond...da-da-dum!', and he started screwing around at the piano.  Within 10 minutes, he had that song written."
Just goes to prove what I've always suspected: McCartney can write some amazing music when faced with a challenge and/or has a fire under his ass.

"Paradise City" (Guns N' Roses)

When I was in 5th grade, Guns N' Roses was the biggest band on earth.  I remember our class taking a field trip to the Old Salem colonial historic district in Winston-Salem, NC (which was a big deal, because it was 300 miles roundtrip, and no class at our elementary school had ever done something quite like that before), and we played Appetite for Destruction (1987) on the bus at least 10 times, heading there and back.  So much fun.
There was something about GNR in those days that I liked, before the songs and Axl Rose's ego/waistline got bloated.  Although the band had formed in L.A., they didn't completely fit the mold of L.A. glam metal.  Even at age 10, I kind of knew that the majority of hair bands, like Poison and Warrant, were just a bunch of Led Zeppelin wannabes who'd raided their slutty sisters' makeup cases.  But GNR had an attitude that seemed more punk.  There also were shades of bluesy, raunchy rock à la Mick Taylor-era Rolling Stones.  (Granted, I wasn't able to express it that way at age 10.  But I still knew what I liked.)
And while all of my classmates were going nuts for "Welcome to the Jungle" or "Sweet Child O' Mine," I gravitated to "Paradise City."  To me, it had the perfect balance of a singalong, poppy chorus juxtaposed with gritty verses.  But it really was all about that unstoppable, monster riff by Slash—who is still the baddest mutha to ever pull off wearing a top hat.
I recently stumbled upon an interview with Slash where he was reminiscing about the song and one-for-all camaraderie of the band in its early days.  He notes that they were riding in a rented cargo van, making the 6-hour drive back to L.A. after playing a gig in San Francisco.  He was noodling around on his guitar in the back of the van, when he began playing the almost-countryfied, fingerpicked intro to the song.  His bandmates eventually fell in on their guitars, and the arena-ready chorus started to take shape on the spot.  (If you're interested in hearing what the original, totally un-PC lyrics were for the chorus, click on over to Slash's interview with Fuse online.)
Ultimately, the chorus became about Rose and bandmate Izzy Stradlin's memories of growing up together in Lafayette, IN (Take me down to the Paradise City / Where the grass is green, and the girls are pretty), whereas the verses became a snapshot of the band's struggle to succeed while not letting L.A. eat them alive.  Quite honestly, in an era that was not known for intelligent lyrics, "Paradise City" is a refreshingly smart song.
If I have one critique of the track, though, it's the obvious splice that happens in the coda (at around 4:42).  Even as a kid, it would drive the audiophile in me nuts when Rose hits that high note on Hoooooome, and then the track obviously cuts to a different take of him screeching the same thing before the band begins to thrash.  
Luckily, the unhinged final two minutes of the track more than make up for it.  
In fact, anyone feel like moshing?

"Sweet Jane" (The Velvet Underground)

"Accessible" isn't a word that one uses when talking about The Velvet Underground.  Lou Reed & Co. never aimed for the mainstream.  Gutters, alleyways, and anywhere where the light was dim—that was more their territory.
However, after years of not selling any records, the band made an attempt at a pop album called Loaded (1970).  On it, is the track "Sweet Jane," perhaps Reed's most effervescent, accessible composition of all time.  Unlike a lot of songs in the band's catalog, you don't really have to get acclimated to "Sweet Jane" before it reveals its charms.  It hits you in the gut from moment one with its lean, mean riff, which lets you know it's destined for rock & roll immortality the moment you hear it.  (It's my personal favorite Reed riff, edging out "I'm Waiting for the Man" by a hair.)  
Nevertheless, Reed can't help himself from getting a little gritty, throwing in the suggestion that seemingly buttoned-up protagonists of the song, Jack and Jane, like to try on each other's clothes  (Jack's in his corset / Jane is in her vest).  To me, it was his way of pointing out that the mainstream is just as freaky as the fringe, even though outward appearances might lead you to believe otherwise.

"Loser" (Beck)

I didn't know what to make of Beck's "Loser" when it first hit MTV in 1994.  Between the D.I.Y.-feel of the video and the bizarre lyrics, my gut reaction was that it was a parody.  But a parody of what?  It had a slight hip-hop feel, what with that funky breakbeat churning away on the track.  The acoustic slide guitar kind of put it in the territory of the delta blues.  But then there also was a "my dog died, and my wife left me" stoned Country Western vibe to it, too.
After hearing it a few (hundred) times, I realized that it wasn't poking fun at any one thing; it was poking fun at everything, and it was doing so using this grab bag of misfit motifs in a way that masked just how intelligent Beck was.  (More on that in a sec.)
Story is, the song came about by chance.  Back in the early 90s, Beck moved to L.A. after a stint in New York, where he'd spent several years trying to make it as a folk/punk musician.  He was living hand-to-mouth, working odd jobs for very little money and then playing acoustic shows at bars and coffeehouses in between, whenever someone was willing to let him on stage.  In order to get people's attention, he'd make up bizarre stuff on the spot, just to see if people were listening.
As he told Rolling Stone in 1994, "I would always sing my goofy stuff, because everybody was drunk, and I'd only have two minutes."
Anyway, in 1992, his goofing around caught the attention of Tom Rothrock of indie label Bong Load Records, who ended up inviting Beck to hang out with hip-hop producer Karl Stephenson.  Long story short, Beck and Stephenson came up with "Loser" at the latter's house by fooling around with different sounds, loops, and improvised lyrics.
The song sat on the shelf for well over a year (Beck didn't think it was particularly noteworthy), when Bong Load finally released it in 1993.  To Beck's surprise (and eventual dismay), it took off as a "slacker anthem" on West Coast indie radio, which drew the attention of music mogul David Geffen, who came calling with an offer to sign Beck to his DGC label.  In 1994, DGC re-released the single, and it famously became a hit across the country.
The feeling at the time (and I admit, I felt this way, too) was that Beck was some jokey one-hit-wonder who had nothing else to say.  Apparently, he also knew the public's perception, and it bothered him.  A lot.  
As he told Entertainment Weekly in 1997, "Being attached to a highly disposable segment of the popular culture—the one-hit wonders, the cartoon slackers, the video phantoms—it's a little troublesome."
He ultimately had the last laugh by releasing the unexpected, brilliant Odelay in 1996.  
In fact, if it weren't for Odelay and his consistently solid career since, I don't think I'd be able to look so fondly upon "Loser."  It's kind of like being able to go back and laugh at your old, awkward photos from 7th grade because you know that everything turned out okay.