"Watermelon Man" (Herbie Hancock)

Nothing really prepares you for the first time you hear "Watermelon Man" off Herbie Hancock's 1973 album Head Hunters.  That's particularly true if you're already familiar with Hancock's 1962 original from the album Takin' Off, which is basically a blues set to a swinging, hard bop beat—his attempt to capture the sounds and rhythms of his youth, hearing watermelon vendors maneuvering their carts through the cobblestone alleyways of his native Chicago.
But the Head Hunters track has a different vibe altogether.  It trades a bit of the playful nostalgia of the original for 1970s urban grit, recasting the tune as a laid back slice of electronic funk.  Along with the radically reimagined arrangement, the 1973 track features this otherworldly whistling/howling called hindewhu, a mouth percussion technique that comes from the Ba-Benzélé pygmies of Central Africa.  (It's that sound you hear at the beginning of the track.)
As I learned in a jazz music appreciation class in college (and had to research again because that was a few years ago), Hancock and his percussionist Bill Summers had first heard hindewhu on a field recording of the Ba-Benzélé and were floored by it.  Although the pygmies produce the sound by blowing into whistles made of hollowed-out papaya branches, Summers figured out a way to imitate it by blowing/vocalizing across the mouth of an empty beer bottle, directly into a microphone.

"Chameleon" (Herbie Hancock)

Until his Head Hunters album in 1973, Herbie Hancock mostly had been known for his bop and modal jazz work with his own bands and with Miles Davis.  He'd flirted with electronic instruments and funkier sounds on several experimental albums in the late 60s/early 70s.  But on Head Hunters, he went headlong into electric funk, inspired by the copious amounts of James Brown and Sly & The Family Stone that he was listening to in those days and transcendental meditation.  
Hancock recalls his decision to move toward funk in Chris Smith's 101 Albums That Changed Music (2009). "I was beginning to feel that we (the sextet) were playing this heavy kind of music, and I was tired of everything being heavy. I wanted to play something lighter."
As reedist Bennie Maupin recounts to author George Cole in The Last Miles (2007), the track "Chameleon" developed out of jam sessions that led up to the recording of the album:

"My participation was the little horn melody.  I had gone to a Wattstax concert…During the course of the afternoon, people would get up and dance. There was this dance that became popular called the "Funky Robot," and I was watching the kids doing it. I was studying the body movement and looking at the rhythm, and some patterns start coming into my head. So when we got back to the studio, somehow that stuff started coming out. We had the tape on and during a break.  We listened back, and it was pretty much by consensus that we should take a closer look at this one theme!” 

The name "Chameleon" ostensibly comes from the fact that the song, like a chameleon, changes in color and texture as it goes along, starting off as hard funk, transitioning into a hustling, bop-influenced jazz jam, and then transitioning back to the hard funk theme before fading out.
Probably the most famous part of the song is Hancock's keyboard bassline, played on an ARP synthesizer—the kind that Stevie Wonder was using on hits like "Superstition" about the same time.  But the equal contributions of drummer Harvey Mason, bassist Paul Jackson, and Maupin make the track the fluid, booty-shakin' jam that it is (which is why Hancock credited the song to the entire band).

"Cantaloupe Island" (Herbie Hancock)

You can't help but admire Herbie Hancock as an artist.  
He was a child prodigy who, by age 10, could play any classical piece anyone threw at him.  Then he became famous playing with Miles Davis in the early 1960s, making a name for himself by combining a feel for the blues with his ear for classical composition.  Then, as Davis nudged him toward the Fender rhodes in the late 60s, Hancock went full-on into tha Funk before reinventing himself yet again as an R&B futurist/hip-hopper.
Anyway, as much as I appreciate his "gather no moss" work ethic, I still enjoy his early post-bop stuff.  It's still so inventive, fluid, and rhythmically complex.  
I especially love the song "Cantaloupe Island" from the album Empyrean Isles (1964).  It has this great syncopated groove that tugs at your ear, making you think it might not be in straight 4, even though it is.  That running Latin-tinged riff throughout also lays down a foundation that allows cornettist Freddie Hubbard to play the melody straight or go off exploring wherever he wants.  That little repeating pattern gets etched in your brain so that, when Hancock goes off and solos and is only playing the skeleton of the riff with his left hand, you think you still hear it.  The presence of it is still there, even though the foundation is only being held up by Ron Carter and Anthony Williams on bass and drums.  
It's genius.
Like most people my age, I discovered the song via Us3's "Cantaloop," which sampled Hancock's core piano riff.  At the time (1993), I couldn't get enough of "Cantaloop" and its pastiche of samples that were cobbled together from various Blue Note Records sides.  But as time went on, its novelty wore thin.  In hindsight, the verse by the MC (who can even remember the dude's name?) wasn't that great.  The sampling paled in comparison to the kind of mind bending stuff that Ali Shaheed Muhammad and Pete Rock were doing at the same time, even though they were sampling some of the same jazz records as Us3.
But that "Cantaloupe Island" riff stuck with me.  It's the kind of thing that I'd find myself humming or playing on the piano to warm up my fingers.  "Cantaloupe Island" also was the gateway to me searching for the sources of the crazy jazz samples I heard on A Tribe Called Quest/Gang Starr/De La Soul/Digable Planets/etc records and buying up tons of jazz recordings from the 1950s-70s in turn.