Rose Levy Berenbaum's Pie and Pastry Bible is excellent! It is fairly specialized, but it's full of terrific recipes for pies. Berenbaum's Flaky Cream Cheese Pie Crust is the easiest pie crust I've ever worked with, and the recipe I've used since I found it. The Open-Faced Fresh Blueberry Pie recipe is also one of my favorites when blueberries are cheap. (I think there are a few other recipes from this cookbook on epicurious, too.) This is the cookbook I turn to when I want to make a summer fruit pie.