Running: legs, and back & obliques
Biking: Ass, abs & legs
Swiming: pretty much everthing, but make sure that you are doing it hard
(butterfly & breaststroke will really get your pecs.)
Martial Arts: pretty much everything, make sure your really do some reps (w/ technique though)
Tennis/Racquetball: excellent overall
Basketball: good legs & arms, you really get a good one with a pick-up game
Aerobics: nope...never liked it, boring
Dancing: Babes, raw energy & better bod for you...what more can you ask?
I'm sure there is more...
But that's what I like.
