I love Madhur Jaffrey's books. She has "World Vegetarian," which includes Indian, but I use her Indian Cooking (I think that's the title) all the time. It is pretty meat centered, however. But the vegetable recipes are almost all fabulous.
I like moosewood, too.
I also like Rick Bailess Mexican cookbooks. That guy really knows his stuff. It is complex food, and labor intesive, but so delicous. If you are vegetarian, there are some good ideas in his books, though a lot of his food is meat centered.
I also love Baking with Julia. That's probably my all time favorite, as far as transforming the way I bake.
Believe it or not, my most used cookbook is the Vegetarian Cooking one in the Sunset series. In fact, I need to get a new copy soon because it's in pieces. I like it because the recipes don't call for any "silly" ingredients that I never have on hand, and nothing is too complicated. I especially love the soup recipes.
If you are up for the challenge and have the time (and have children??!!) the Millenium all vegan cookbook is a trip! I have slowly gotten into it while getting past the complex recepies.. But the food is to die for..
I have a stack of cookbooks, but have gotten all of my favorite recipes from vegweb.com and allrecipes.com. If you read the comments on the recipes, you can usually pick the really good ones and find ways to modify the recipes.
I love love love the Barefoot Contessa!! There are 2 books, and I use them all the time. The recipes have tested thousands of times in her gourmet shop, and the food is really straightforward, honest and delicious.
I also like the Deborah Madison book, and of course the Mousewood ones, esp. the dessert one
_Betty Crocker Picture Cookbook_, first edition
Now available in facsimile edition if you don't have a hand-me-down
And for Indian vegetarian, you can't beat _Lord Krishna's Cuisine, The Art of Indian Vegetarian Cooking_ by Yumuna Devi. I've had friends from India ask for recipes--it's comprehensive, exhaustive and excellent. But you won't find meat or garlic.
Best nostalgia vegetarian or the cookbook to use when carnivores come to dinner, _Tofu Cookery_ by Louise Hagler--lots of modern stuff, but you really can't beat substitutes for those old standbys grandma used to make like tofu pot pie (in lieu of chicken) and tofu barbeque.
Of course, I also love the Moosewoods and the Vegetarian Times, the Sunset Vegetarian has also gotten a good workout.