Have a look at Mirah[1] a statically typed ruby-like language that runs on the JVM, by Charles Nutter, the main jRuby developer. Here's an article [2] with short descriptions of Mirah and other Ruby-dialects or Ruby-inspired languages

[1] http://www.mirah.org/

[2] http://www.igvita.com/2010/12/14/beyond-ruby-mirah-reia-rite...