user defined collections

What modules would I use to build a website that ...

1. has 100s of photos that can only be added and modified by an admin [i.e. not the majority of users]
2. allows users to find and group photos into their own custom made collections
3. leave and come back to view their own collections as well as collections made my others
4. edit their own collections
5. then share their collections with others

Thanks,

Rex Kilian
Human-Computer Interaction Institute
Carnegie Mellon University