Indoor Exercise*

Right now I'm in China, kind of stuck indoors (and besides, it's way too polluted outdoors to exercise...) and was wondering for any other suggestions for exercise besides pushups. This is also to help me brainstorm ideas for when I go to college this September. I'll have a pullup bar when I go to college, though.

Question 2: Does it matter if I have a set 'routine' -- like doing 'sets' or 'reps' ? I've always just done pushups or pullups randomly throughout the day. Is there a difference in efficiency or quality of the workout?