I just read one of the best biographies ever, an autobiography of Malcolm X. Apparently it is rated by Time magazine as one of the 10 best Non-fiction books of the century. It's a very good insight on Malcolm and his lifestyle helping out the blacks, and going through great amounts of physical strain to do it. Def. a good read if you can get a copy of it!
If you liked that I would also suggest reading Soul On Ice by Eldridge Cleaver..some of the stuff leaves you scratching your head, but there is a lot to make you think as well.