Which Books behind Bars?

I've seen a flyer at Antigone Books in Tucson about a Books behind Bars project or something like that that sends books into prisons.  I think its a great idea but another incident made me start thinking, which books?

One day I took a walk in the Santa Cruz wash, happened to be after a city sweep of the homeless camps.  They had pretty much bulldozed them, so leftover things and trash were scattered around.  I found a book, that one of the homeless folks had owned.  It was some kind of psychic text that sort of blamed problems on society in a kind of ranting way.  I can't remember the name of it now but it struck me that this book probably wasn't going to be the one to help someone get their life back together.

On the other hand, some books are truly powerful and inspirational.  I posted somewhere else about the prisoner with a quote from Anne Frank's diary tattooed on his back.   And that is not even one I would have chosen.  Maybe Victor Frankl?  My Shadow Ran Fast by Bill Sands?

I am curious, what books people have found to be really helpful in changing their lives.  Especially that would be relevent to prisoners today.