Here are a couple of great, free downloads to help you ID a few more birds during the migration season:
http://blog.press.princeton.edu/2013/07/25/downloadable-warbler-guide-quick-finders/ On warblers
http://blog.press.princeton.edu/2013/10/04/kick-your-warbler-id-skills-up-a-notch-with-this-free-tip-sheet-on-aging-and-sexing/ again on warblers.
http://blog.press.princeton.edu/2013/02/19/download-your-free-crossley-id-guide-samplers-pdfs
On backyard/feeder birds and raptors.
Thanks to the crossley ID guides for giving these away, and to my dad for informing me about them.