if you wanna build your upper body (chest, back, arms), try doing hands-only pushups. that is, stand in a non-vertical position (inclined a bit) on your hands only, and try to push yourself up. its hard, and takes some practice, but its a workout and a half
also, do some dips using chairs and tables or whatever. that'll work you out a bit.
ps if youre interested in the hands-only pushups and how to be able to do them, pm me