Here's a discussion we did recently on stir-fry cooking: ISO Asian stir fry type recipe
This was my first Asian cookbook other than a really complicated one my BIL gave me years ago: Stir-Fry Recipes
I love it. It has a lot of simple recipes and tips for stir-frying technique, ingredient combinations, and substitutes.
I also find this a great site for recipes and inspiration: SteamyKitchen.com