I just got my beta invite to Riya, a photo sharing site that has a very cool feature - facial recognition. While the government is using this for evil purposes like finding you at airports and football games Riya has put this technology to a much better use.
When you upload photos to Riya, it starts scanning them for possible faces. There is an easy to use interface to choose from a list of known names, or assign a new name to a face in a photo. Riya recognizes multiple faces in photographs also. It found faces in all the photos I uploaded except in one that had a profile view instead of a front view of a face. Oh, and a photo of a squirrel. I guess they all look alike?
I could probably come up with a list of "needed" features and changes, but this is still beta, and they are really testing the recognition side of things. Adding better photo management and other features is pretty easy with well-indexed sets of photos, so once this testing is done, I'm sure these features will appear quickly.