Admin section would allow you to change the upload folder size. Basically, the structure could work like xCGal does. Each user gets their own folder created. This will help a lot, especially when people upload a filename with the same name. No overwriting and no renaming because someone else uploads the same filename.
It would also allow the admin to make size limitations by group, just like xCGal does. For instance, groups who are just regular artists could be set at only 15 megs of space. Groups who were Premium Artists, could be set at 30 megs, or something to that effect. Also, making the option of "Approval Before Posting" is a vital feature. This will definetly help cut down when it comes to users who upload copyrighten stuff (provided you recognize the material, that is).
File size limitations would also be good.
Prepare for lots of ideas to be flowing from me over the course of this module design lol. I've wanted something like this for about a year now, but never actually asked about it.