comp.lang.ruby - join
The Ruby dynamic OO programming language.
High activity, 7743 subscribers, Usenet

ruby-talk-google - join
This is a mirror list of the offical ruby-talk mailing list. It serves as a alternative to the mail<->news gateway (comp.lang.ruby). It exists to provide access to the mailing list via the convenience of Google Groups web-based client.
High activity, 3165 members

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