"Do Your Thing" (Isaac Hayes)

There was so much more to the late Isaac Hayes than just being the voice of a cartoon chef on TV.  The man was a pioneer in soul music, not only penning hits for the duo Sam & Dave ("Hold On, I'm Coming," "Soul Man," and "I Thank You") and backing Stax Records artists like Johnny Taylor and Carla Thomas in the 1960s, but also redefining what soul music could be heading into the 1970s.  
He was one of the first soul artists to eschew the radio-friendly single.  Limit a song to 3:00?  Screw that.  He was crafting jams that ran for 10, 15, 20 minutes that sprawled across entire sides of his albums.  
He completely rearranged, reinterpreted, and funkified MOR ballads like "By The Time I Get to Phoenix" and "Walk on By" (look for it later on this list) with a mix of gospel harmonies and rhythms, psychedelic rock guitar crunch, and jazz improvisation--ushering in a new era of the Stax/Memphis sound.
The pinnacle of that sound was the Shaft soundtrack album.  Everyone from your infant cousin to your old-as-Methuselah grandpa knows the title track.  But many have no idea just how fresh it was at the time, or the fact that it won Hayes an Academy Award for "Best Original Song."  That's probably because its once-innovative chicken-scratch, wah-wah guitar (provided by the late guitarist Charles "Skip" Pitts) got co-opted by every greasy composer writing backing music for cheesy cop shows in the late 70s, which had the unfortunate effect of reducing the original to parody.
But beyond the title track, there's a song taking up most of Side Four of the original double album: "Do Your Thing."  It begins simply enough with a soulful horn riff and cross stick pattern on the snares.  But then "Skip" Pitts's fuzz guitar with the tremolo turned waaaaayyyy the hell up slinks in, and you know what you're about to hear is baaaaadass.  
Then, Hayes's baritone comes in with the lyric.  It's nothing too philosophical or groundbreaking, the message being: if you're good at it, if it brings you joy, or if it helps you relieve some pressure (whatever it is), then do your thing.  It's not quite as anthemic as, say, James Brown's "Say It Loud" or even quite as decadent as BT Express's "Do It ('Til You're Satisfied)" from 1974, but it gets the point across.
The vocal portion more or less ends around the 2:30 mark, and thus begins Pitts's raunchy, fuzzed-out soloing.  On the single version, you get about a :30 taste before the solo fades out.  But on the album version, things are only getting started: Pitts solos for 16 solid minutes as the rhythm section locks in to this gangsta lean groove, finally culminating in this psychedelic freakout that includes Hayes blowing kisses into the mic, the children's song "Frère Jacques", and the NBC "chimes"(!) before a needle scratch sound effect brings it all to a jarring close.
It is wild, deep, funky stuff that is worth every one of its 19 minutes.  Classic.