you can do anything with strength bands you can do with weights. its also much much cheaper you just need some doorways or a post to attach it too.
http://www.build-muscle-guide.com/terrell-owens-bands.html
also you can get
http://www.trxtraining.com/
Both are pretty much the same thing although you can get real creative with the trx for core workouts ect. Both are much cheaper than a full gym would be and fit in a small bag for storage.