I have three volumes of an excellent Funk compilation called "Funk Spectrum" (BBE Records, UK, 1999 - 2001), there are three (four?) of them out IIRC.
The comp. was made by Kenny Dope and Keb Darge... Funk through the ages, if you will, from the 60s Funk a la Sly & The Family Stone to newer 80s stuff.
I also love Defunkt, my fave album is "Avoid the Funk: A Defunkt Anthology" (Hannibal Records, 1991), it's more on the harder side.
Oh, and check out Stax records archives, they're packed full of cool funky sound. Motown is good as well, but they released way more soul than funk.
Clinton and his P-Funk stuff are a mixed bag for me, there are some really good songs but some of them are a bit too gimmickry for my taste... I like the Funk that is closer to Jazz than to electronic music or soul.... anyway, his "One Nation Under A Groove" album (Funkadelic) is a must-have IMO, and be it just for the silly cover.
EDIT: Almost forgot the best of them all - Herbie Hancock, please man, do yourself a favor and check out these albums: "Sextant", and ...drum roll... THRUST. Reeeaaally funkay.