Creating a collaborative/social network image site?

[minakichan]

I have an assignment for Intro to Media Studies to create some kind of collaborative web project. The idea my partner and I have is kind of an art image manip site-- users post their art or random photos and images, and others upload their edits or manips of the original image, and still others edit/manip those, etc. The teacher likes the idea, but I guess I don't really know how to pull it off-- I only really know Web 1.0 stuff and don't have the time to implement this from scratch anyway, so I'm looking for tools.

Essentially, I'm looking for a way to create a small social network-- or better yet, an image board like 2ch-- that I can adjust to fit my needs (something really image-heavy) and I guess the only way I can think to implement this project is with something that supports nested comments. I've looked around, but big name things like Ning and the 2ch imageboard model don't allow this; the closest thing I've found is LiveJournal, but I'd like to see if something more customizable exists. Any suggestions?