I just found this site that helps you identify over 1,000 species of birds in the U.S. and Canada. It is a step-by-step ONLINE field guide that can have you identifying your unknown birds in minutes. It also has a store where you can get some really GREAT stuff for your bird garden. I am interested in their solar-powered bird bath fountain pump that pumps 40 gallons per hour and costs only $65.00 USD! Splashing gurgling water in a fountain, pond, or birdbath will attract many insect eating species that would NEVER come to ANY of your birdfeeders, so a NOISY, wet, water feature is essential to attracting the maximum number of DIFFERENT bird species to your yard or garden. Here is a link to their site.
WhatBird