Usually from 12 -20 in a set on my toes, depending on where they fit in the workout (if I'm already tired out from other chest work, it's in the low range). And on some days, I do better than others.
P90X REALLY helped me get to that point!
And I do all 72 (!) of the push-ups in GS, but I put a longer break between sets (o.k., I guess I "cheat"!) so I can do them all on my toes. (somehow, that "break" get longer and longer between each set!)