Like a member said above: check out James Brown's 20 Greatest Hits. James Brown is not only the Godfather of Soul, he is also the Master of Funk; its originator. Songs like "Sex Machine, "Get Up Offa That Thing", "Get On the Good Foot", and "The Payback" are all top-notch, vintage funk songs done by the master himself.
Shortly, after James Brown started getting funky, Sly and the Family Stone followed that path. Although I don't consider them the ideal funk group, they still had a myriad of funk beats that anyone could groove to. A good example is "Poet", not the bombastic, frenetic funk done by J.B., but a much more relaxed beat, Larry Graham, the bassist for the band, carried the groove like no other.
On that note, Larry Graham, one of the most renowned bassists in funk/R&B, had a solo project titled Graham Central Station. While most of the music was second-rate and a tad on the cheesy side, he had a few memorable funk beats. "The Jam", "Don't Stop When You're Hot", "You're a Foxy Lady", and while it isn't the most funky tune, "Sooner or Later" was a great song that should've been pushed to be a single.
Larry Graham, along with his impeccable ability to carry a groove and his unique slapping technique, had a great baritone voice. No matter who you are, no one can do nothing but move when he works his magic on the bass.
The next, and probably the most obvious group, would have to be Parliament/Funkadelic aka P-Funk. With the colorful George Clinton leading his horde of funky afroteers from outer space, they came to educate all in the art of funk. And they did.
P-Funk is responsible for some of the funkiest beats known to mankind. With some excellent, funky guitarwork, groovy synth beats, carried by another master of the bass, Bootsy Collins, this music was devastating.
Check out, "Aqua Boogie", "Flash Light", "P-Funk(Wants to Get Funked Up)", "Dr. Funkenstein", and "The Mothership Connection". Those are just a few of the funky tunes these cosmic funkateers crafted.
Bootsy Collins, also has some solo material out there titled Booty's Rubber Band. Though it's difficult to find, it's a treasure to possess in your collection of funk.
Other notable mentions are Brothers Johnson, Zapp (or Zapp and Roger), Lakside, and Prince. Yeah, believe it or not, Prince has quite a few funky songs.
And like someone said above, the Red Hot Chili Peppers have a lot of funky material. "Funky Monks", and their most funky song ever, "If You Have to Ask", are two of the great classics off of Blood, Sugar, Sex, Magik.
Enjoy my fellow brother in funk.
P.S. I can't stress enough how much you need to listen to Red Hot Chili Peppers' "If You Have to Ask", it is beyond words it's so funky. Now go get enlightened by all the funk I suggested.
