Body weight training: prison style

I've read these books, and they provide a myriad of body weight exercises and stretches that some ex-con thought up while in jail, or at least that's how the story goes.  I do some of the upper body strength training exercises the author describes, but I think the real benefit of this book is the stretching regimens.  It's where I get my spinal stretches from.  Anyways here's a link to Convict Conditioning and Convict Conditioning 2.  They're both good books. Give them a shot.