Jimi Hendrix was a super sneaky rhythm player. Another guy I like and who never gets mentioned (and in fact I don't even know his name) is Macy Gray' guitar player. He's always always in the background doing some tasty Stax approved rhythm fill or Steve Cropperism. I'm not a big fan of modern R&B but his playing inspired me to buy that first album of hers, which is really good.
Nobody could mix rhythm and leads like Jimi, he made it look effortless.