He wrote a/an MMORPG in 100000 lines of Java: http://en.wikipedia.org/wiki/Wyvern_(Online_Game)
He also ported Ruby on Rails to Javascript: http://steve-yegge.blogspot.com/2007/06/rhino-on-rails.html
He also ported Ruby on Rails to Javascript: http://steve-yegge.blogspot.com/2007/06/rhino-on-rails.html