For one, check out anything by
The Poets of Rhythm... they're not that well known, but they're like James Brown on steroids (or something!). VERY funky.
I first got turned on to them when I picked up this album:
Ironically, the album says "acid jazz", which is why I tried it out when I picked it up in the store, but it's not acid jazz at all. Trust me, it's greasy funk!! I highly recommend it as a starter disc.