Added to official ideas list at http://drupal.org/node/237628
Overview: With Encrypted RSS/Atom feeds, buddylist-like features become possible cross-site. The project would be to develop a module which generates and consumes syndicated feeds, where reading them in only possible behind a login.
Details: With all of the social networking sites these days, decentralized ways of connecting across communities are still being developed. One thing that's impossible now is sharing private blog posts with someone outside of your group. This project touches on social networking, encryption, both of which are fascinating, topical and good on a resume :-)
Drupal is a perfect platform for this, because of the wide use across micro-communities. With this module, two separate bloggers that use drupal should be able to share their private posts with each other without necessarily requiring a user name.
With this in place, future directions could lead to browser plugins which decrypt these feeds/microformats on a page with public keys.