Like the title says, Zack Rosen of CivicSpace is trying to rally support for the og2list module. Here are some quotes from the reverse bounty post on Drupal.org:

Og2list is an add-on module for Organic Goups. It will provide full blown mailinglist support for groups created within a Drupal website. You can see a demonstration of early og2list functionality in this screencast. We hope to add og2list support to groups.drupal.org when development work is complete.

Why do you want to help fund this add-on module? Well, that's the beauty of open source. Fund it once, and it becomes available for everyone. Zack goes on to explain why this type of functionality is important.

We think og2list will be a very important contribution of critical functionality to the Drupal project. While we are living in the age of "Web 2.0" web-application innovation, most collaboration that takes part in online communities is still facilitated through mailinglists. Properly integrating mailinglist functionality inside a Drupal platform will allow communities to leverage the best of both worlds; the timeliness and convience of email based collaboration combined with powerful features only avaliable through the Drupal platform.

Get in touch with Zack if you're interested in donating.