Yeah, this would be one of the best futures on my CPG system also!!!
I'm making photos of people on diverse situations at parties and on the street. So, when one of the photos are used for a magazine, I need to have a modelrelease of the person on the photo. So this is what I'm thinking about:
- Shoot the photo
- Give them my website
- They register
- They Login
- They search for the photo
- Point with cursor on the photo who they are.
- Under the photo will be the Name of the persons...
It can be also some kind of dating site system... but that's for the future.

My idea to devellop it:
- table with user_photo info
- wich person on wich photo (there can be more than one person on 1 photo)
So technically something like to use the coordinates on the photo and the horizontal position of the person to use for the position of the photo.
For an example of this function you can have a look at one of the biggest Party community in the Netherlands:
That's me with my girlfriend...
http://party.snt.utwente.nl/flock/SECTION/gallery/ACTION/one/PUSERID/19641/IMGID/108515.html