The first book everyone will tell you to read is Liber Null and Psychonaut by Peter J. Carroll. It lives up to the hype. If you want a pdf copy let me know and I may know where you can find one. With Miskatonic Library recently having their tumblr account closed for distributing copy-written books, I’m not taking the chance of posting it here.
Most people leave you hanging after that. The second book I recommend you read is Oven Ready Chaos by Phil Hine. He gives that one away here: www.philhine.org.uk/writings/pdfs/orchaos.pdf
Then you’re ready for Liber Kaos, Psybermagick, The Apophneion, and The Octavo by PJC and Prime Chaos by Phil Hine.
One resource that has been a great inspiration to me is not a book but a speech given by Peter J. Carroll called General Considerations on the Philosophy and Practice of Magick. You can find that here: https://docs.google.com/leaf?id=0Bx9jMDq9aWMIOWI0ZTA4NzktODgxYS00NDAxLWJkNDQtNDA1NmI4MzYyY2M2&authkey=CLLBteoF&hl=en_US&authkey=CLLBteoF