I would like to see the ability to include multiple attachments per posts, with individual descriptions. There's a fantastically well made attachment mod for phpBB done by someone at this site:
http://www.opentools.deI would like to see something as functional as that. Not only can a user post multiple attachments, but each includes a description, the file size, and number of views. Images have the option of being displayed inline. It also includes full management with statistics, limits, quotas, and storage of attachments on an ftp server.