Cooking for One Cookbook?
I'm single, and I cook about 90% of what I eat myself. Someone gave me a Williams-Sonoma "Cooking for Yourself" cookbook a few years ago. It's one of those thin, hard-back cookbooks with lots of pictures. It's pretty decent... not my favorite cookbook, but it's got a few good recipes and I picked up a couple of tips from it (like using a cheese grater to get tomatoes ready for a sauce). The pictures are nice... lets you know what you're in for. I haven't made anything from it in a while... I should probably break it out again sometime.
But really, the best thing to do is just become independent of cookbooks as much as you can. I use Joy of Cooking as a reference and to get an idea for basic recipes, and the Food Network website is good for ideas. That's it though... no need to stick exactly to a recipe unless it's your first time making something.
It's pretty easy to scale most things down, but sometimes there's no getting around making more than you can handle in one meal... soups, sauces, bbq, pizza, etc... Sometimes you're just going to have lots of leftovers... Life is a series of compromises.