One of Drupal's short-comings has traditionally been the lack of contributed themes as compared to other projects. One reason for this is that in order to contribute a theme, a designer must first come up to speed on using Drupal.org's revision control system (CVS). This is often too high of a barrier for most designers, and Drupal ends up losing out.
This project would require developing a module that provides web front end to CVS, so that themers (with proper access) could simply upload an archive file (.zip, .tgz) file, enter a log message, and set some options (such as which version of Drupal the theme is for, and an optional accompanying screenshot). The archive would be then be expanded and committed to CVS behind the scenes, and an initial theme project release created. Each additional upload would result in an additional CVS commit, with files modified, added, or deleted as appropriate, and create an additional project release.
This should be done in an extensible way so that it could conceivably apply to other project types, such as translations or even modules.