Good Field Guides for Birding
I don't want to make this sound like its some sort of spam (because it is not), but I cannot recommend highly enough the Crossley ID Guide for Eastern Birds for anyone wishing to hone their eastern North American bird watching skills.
I have no field guide as overall useful as this one. The guide shows actual (overlayed) full-page photographs of species in their respective typical habitats. All ages, genders, and plumage variations (not to mention different viewing angles) of each species are included.
I saw that a new raptor-specific edition is going to be available in March. I am ecstatic!
That is my recommendation. Do you have one to share as well?