Before you dismiss body weight exercises answer this: Can you do 8 proper chin ups and 8 proper full body weight dips (no feet on bench)? That's what I thought.
Done right 99% of people can get a great workout using no weights. Read this for more info on these types of workouts. I've been clear on how I think yoga builds muscle, and lastly this is a very demanding (I know because I tried it) no weight workout from Women's Health.
These are great moves for 2nd phase lifters and can be a nice "change of pace" workout for people that have moved into 3rd phase lifting as well.