Trading in the zone by M.douglas
Price Pattern by Martin J Pring
Van Tharp on Money Management
Japanese Candlestick by Steve Nison
But all those books above related to how to trade...if by any means that u want the book that describe the forex world such as the bid and ask price, swap, leverage, spread, currency pair, liquidity, you can try here on ff rookie section.
I liked the patterns book mentioned above and I also enjoyed Adventures of a Currency Trader by Rob Booker. It's a trading psychology book...a fun read.
If you really want to learn something, I would suggest checking out Rob Booker, Peter Bain and Hector Trader. They have some free online stuff that you can check out. That is how I started learning and I still learn from them.
And of course read the forums here...there are always some good ideas.