I have had a blast on our DC trip making panoramic photos with Microsoft’s Photosynth application. The basic idea is simple: you point your iPhone at something, move it according to the on-screen prompts, and get a beautiful panorama when you’re done. Here’s an example: the Great Hall at the LIbrary of Congress.
Photosynth makes it really easy to take panoramas, and it does a fine job of stitching them. I’d love to see this app running on a device with a better camera (hint, hint, Windows Phone 7 from Nokia…) but it’s well worth the price: $0.
If you want to see the panoramas I’ve created so far, they’re here.