I forgot one! I didn't think about it because I was concentrating on artists/bands, but this comp deserves a mention.
V/A -
Cold Heat: Heavy Funk Rarities, Vol. 1: 1968 - 1974 (2005)
A few months back, a friend invited me to a rare soul/deep funk dance night and I had the best time. The very next day, I asked for recommendations on another forum I visit daily, and this was one of many that I received. It's the one that made the best impression on me, the one I can really get down to! Really amazing stuff.