Mixbook is a Flex based application that allows you to create printed photo books, much as you can with iPhoto, with a few interesting twists. As Ryan Stewart mentions in his blog, this is an interesting twist on Web 2.0 - no ads, no subscription costs; Mixbook makes money by sending you a physical good.

Unlike iPhoto, Mixbook allows you to work collaboratively with other people in making the book, so the onus for creation isn't on one person. You can easily invite other people to your book, and then collaborate with them to create the finished product.

The finished product is available in two forms, the printed book that is shipped to you as well as an online photo book, complete with page turn animations (Sample). Users can rate and comment on the finished online book.

This application would be great as an AIR application. Adobe AIR would add the ability to drag and drop photos directly from the desktop into the application, without having to upload the photos to Mixbook's servers.