How can I make something like flashkit.com?

Hello developers,
Anyone knows a tool / script (CMS I guess) that can help me build something like http://www.flashkit.com ?
I need it to be a file directory that allows me to place files on categories and have previews for different file type like swf, sounds, images. Just like flashklit.com.
Users should be able to upload files. From an admin panel files can be edited, accepted, rejected.

Anyone knows how can this be made?
Thank you.

-Adrian.