You found a feather on the ground when you got home last night, and you just don't know which bird it came from. Enter The Feather Atlas.
It is a website set up by the U.S. Fish & Wildlife Service's forensics laboratory in Ashland, and it provides a place to compare the feather you found with images of bird flight feathers compiled by the site.
Steller's jay or scrub jay? There IS a difference... Pepper Trail from the lab stops by with details of the atlas and what it took to assemble.