I use allrecipes.com a lot (on the rare occation that I cook, as DH is our primary chef here).
As for favorite cookbooks, we have several of the Williams Sonoma cookbooks that are particular to specific places (we have Paris, London, Barcelona and Florence). The recipes are excellent, but can be difficult. But, the pictures are amazing and the books are more about the general cuisine and culture of the place than they are about just different recipes. I love them.