I'm right next to the fifth tree on the right

Were you at the inauguration? Want to prove it to someone else? David Bergman set up a system to take 220 individual photos and stitch them together into a single 2 gigabyte image of Obama's speech. You can navigate through it using controls similar to Google Maps, including zoom in and out (which means it doesn't download all at once). You can even see the music on the stands of the military band (alas, not pick out the notes), find Yo-Yo Ma with his cello at his feet while he takes a picture, and scan the huge crowd for faces. (And, no, I wasn't there.)