(Please expand and annotate this list.)
Drupal.org
Community Initiatives
http://drupal.org/community-initiatives
Groups.Drupal.org
Paying for the Plumbing
http://groups.drupal.org/paying-plumbing (our home-base group!)
Projects Needing Financing
http://groups.drupal.org/projects-needing-financing
I don't know that it has had a successful fundraising in its history. Asking people to join a group and wait for something they want to fund to be posted is not a very good model. See in any case its questions to answer when starting a fundraising campaign.
Projects Needing Volunteer Developers
http://groups.drupal.org/projects-needing-volunteer-developers