There was a some interest in something like that ("text/ruby" support via an applet + JRuby) a while back: http://almaer.com/blog/running-ruby-in-the-browser-v

There was a some interest in something like that ("text/ruby" support via an applet + JRuby) a while back: http://almaer.com/blog/running-ruby-in-the-browser-via-script-typetextruby http://almaer.com/blog/running-ruby-in-the-browser-via-scrip... I remember hearing about it initially, but it doesn't appear to have gotten much traction.