The entirety of David Attenborough's wonderful nature series The Life of Birds is available on the new YouTube TV Shows section, which is its Hulu-clone. The old PBS Life of Birds website is also worth a visit.
The Internet Bird Collection has over 28000 videos of birds from all over the world. The brain-child of Josep del Hoyo (who also started the Handbook of the Birds of the World) it contains footage of more than half of all the bird species in the world, which number around 10000. Just browsing randomly I found such charming clips as a pair of gang gang cockatoos, a pair of preening and feeding Siberian cranes, a hoatzin displaying, Temnick's tragopan displaying, Kerguelen petrel swooping between waves, green hermit feeding on heliconia flowers, in flight, a pair of hamerkops mating display and American avocets mating. Or you can just go look up your favorite bird species and see if they have videos of it. Happily they had plenty of videos of my favorite bird, sterna paradisaea, the arctic tern, and I like this one best. Each bird has taxonomic and distribution information.
John James Audubon's Birds of America with Audubon's original text. It's laid out by family and genus but there is also an alphabetical list of plates which has bigger versions of the bird pictures. There are also links to the state birds as well as birds driven to extinction since Audubon's time.