Oh Graeber's book is out! Lovely! I have been passing around his essay by the same name for some time now. Should be a good intro to the book http://blog.longnow.org/2010/04/22/debt-the-first-five-thous...

I would also recommend anything by David Harvey. Start out with this animated version of one of his talks: http://www.youtube.com/watch?v=qOP2V_np2c0 Then move on to his Capital vol. 1 lecture series. http://www.youtube.com/watch?v=gBazR59SZXk There is also a book format of his reading guide