Web sites
Sloperama's Game Design 101
GameDev.Net
Gamasutra
The 400 Project

Books
Theory of Fun by Raph Koster published by Paraglyph Press

What Videogames Have to Teach Us About Learning & Literacy by James Paul Gee published by Playgrave

Rules of Play by Eric Zimmerman & Katie Salen published by MIT Press

Game Design: The Art & Business of Creating Games by Bob Bates published by Prima

For more great book links see: http://www.next-gen.biz/index.php?option=com_content&task=view&id=3962&Itemid=2