Lich is a cross-platform multithreaded interpreter meant exclusively for use with text-based MUDs. The application natively supports the Ruby language as well as the Simutronics "Wizard" script standard including their StormFront expansions.
JRuby is the effort to recreate the Ruby interpreter in Java. JRuby is tightly integrated with Java to allow both to script any Java class and to embed the interpreter into any Java application. NOTE: JRuby has moved to Codehaus, visit jruby.codehaus.org