"I Feel for You" (Chaka Khan)

I remember when Chaka Khan's "I Feel for You" came out in 1984.  It was the weirdest sounding thing I'd ever heard: there was Melle Mel from Grandmaster Flash & The Furious Five rapping/chanting Khan's name, a sample of "Fingertips, Pt. 2" by Little Stevie Wonder thrown in for good measure—not to mention a live Stevie Wonder, playing harmonica on the track, and then odd tape noises and random effects that kind of left you wondering if someone had leaned on the wrong button during the final mixing.  I listen to this song now and marvel that anyone had the guts to even attempt anything so bizarre (much less that mainstream radio programmers had the stones to play it).
Because Khan owns her performance so completely, a lot of people don't realize the song actually is a Prince composition.  It originally appeared on his 1979 self-titled album, albeit in a much leaner format.  In fact, compared to the late mega-producer Arif Mardin's everything-and-the-kitchen-sink production for Khan, Prince's original sounds almost like a demo.
In truth, Khan's cover of "I Feel for You" came about because her record company had expressed "concern" that she'd released several albums in a row without a definitive hit single.  (In record company speak, that means, "We're dropping you soon if you don't get a hit.")  So Mardin specifically set out to create something attention-grabbing that felt very futuristic, combining the Uptown vibe of hip-hop with the Downtown vibe of electro-pop and adding the element of soulful R&B.
Mardin recounted to NPR's Michele Norris in 2005 that the idea of using Khan's name as a rhythmic element came out of a conversation with Khan's brother, musician Mark Stevens.
"I said, 'You know, you have two sisters—one of them is called Taka Boom, and the other sister is Chaka Khan. Why can’t we use these two names like percussion? Taka Boom-Chaka Khan-Taka Boom-Chaka Khan'.”
Even though the initial experiment didn't quite work, it did establish the groove for the song, and the vocal percussion idea morphed into Melle Mel's rap.
Mardin also revealed that the famous Chaka-Chaka-Chaka-Chaka Khan "stutter" at the beginning of the song (a technique that hip-hop producers jumped on and ran into the ground in the years that followed) was a serendipitous error.
"As we were mounting the recording onto the main master, my hand slipped on the repeat machine.  And we said, 'let's keep that; that's very interesting'."

"The Message" (Grandmaster Flash & The Furious Five, feat. Melle Mel & Duke Bootee)

The development of rap can pretty much be divided into two periods: before “The Message” and after “The Message.”  Before the song hit the airwaves in 1982, 99% of rap was about having a good time and getting the party started  (Kurtis Blow’s “The Breaks,” The Sugar Hill Gang’s “Rapper's Delight,” and Grandmaster Flash & The Furious Five’s own “Freedom.”)  But “The Message” broke the mold as the first mainstream rap record that actually included social commentary.  There was no posturing; it was simply a truthful slice of life from the inner city.
When session musician and songwriter Ed “Duke Bootee” Fletcher demoed the instrumental track and lyric to Sylvia Robinson, CEO of Sugar Hill Records, she decided that it was a perfect vehicle for Grandmaster Flash & The Furious Five.  But the group didn’t agree.  They argued that the laid back groove, which was heavily influenced by Zapp and Tom Tom Club, and the lyrical content weren’t right for their style.
“We [were] used to doing party raps and, like, boasting how good we are and all that,” Melvin “Melle Mel” Glover told NPR in 1992 (rebroadcast 2012). “When the record company brought the record to us to do, we didn’t actually want to do it, and I was the only one that, like, caved in…I didn’t think it would be pivotal either way.”
Little did Glover know that the track would go on to be one of the most influential songs of the 20th Century.
And despite the song being credited to Grandmaster Flash & The Furious Five, only Glover and Fletcher actually appear on the track.  The rest of the group only shows up for a few seconds in a skit at the end of the song, where they get busted by overzealous cops who think they’re gang members.