Ruby on Rails: Talk - join
The official mailing list for the Ruby on Rails project. Where Rails users come to seek help, announce projects, and discuss all kind of matters surrounding the framework and the community.
High activity, 19301 members

Auckland on Rails - join
Enthusiasts of the Ruby on Rails web framework in Auckland, New Zealand. This list is for online discussion, and organising gatherings, talks and other Ruby on Rails events in Auckland.
Low activity, 53 members

DeRailed - Denver Rails UG - join
Denver Ruby/Rails User Group aka DeRailed. The Denver chapter rails community. Build a local ruby/rails community - Share ideas, concepts, innovations - Advertise job openings - Build around passion for Ruby/RoR, humor and good fellowship...
Low activity, 397 members, moderated