Well I don't do gymnastics (yet!), but I play soccer and run track, and I used to play basketball. I plan on doing gym for real this summer tho, cuz it rocks

. I don't think I'll be competing or anything like that tho, I'm mostly doing it for fun.
My gf, who is a Level 8 gymnast, used to play soccer too. But when she got to the point where she was going to have to start seriously committing to her sports, then she had to pick one or the other.
I think time commitments might be the main thing keeping a lot of gymnasts from getting involved in other sports. But I have a feeling gymnasts would probably be good at just about any sport because they are naturally very athletic. Of course Diving and Pole Vaulting, as well as Cheerleading and Dancing are the obvious ones. The girls on my HS gymnastics team that I can think of do all different ones like Field Hockey, Lacrosse, Track, Cross Country, and Volleyball tho.