rubyclr - join
Welcome to the RubyCLR group. RubyCLR allows you to create .NET applications with Ruby.
Low activity, 60 members, restricted

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.
Low activity, 3165 members, restricted

Castle Project Development List - join
Developers discussions
Low activity, 786 members, restricted