My Google Summer of Code 2009 proposal was accepted. The basic idea is to develop at least three modules based on Recommender API. For example, one module is to recommend Flash videos based on users' viewing history like in YouTube. A mockup screenshot is like this:

For more details and discussion, please go to http://groups.drupal.org/node/19894.

(This site is heavily abused by spams, and the captchas don't work well for me. Commenting is temporarily disabled. Sorry about that...)