If you are dedicated to it, you can get good results from just body weight exercises.
I've heard great things about Convict Conditioning, though I've never used it myself. I can also recommend the Nerd Fitness Rebel Strength Guide, which I know has a section on body weight only exercises.
Or if you didn't want to buy a book, I'd maybe pop on the the Nerd Fitness forums and ask about it there. I haven't been on there for a while, but when I was using it regularly, I was quite impressed wi how helpful, accepting and knowledgable the community was.