Ruby off Rails – Some other uses for Ruby (jemaddux.com)

A couple environments that use Ruby but aren't listed in this article

RPG Maker (XP and VX) -http://www.rpgmakerweb.com/products/programs/rpg-maker-vx-ac...

Ruby Processing - https://github.com/jashkenas/ruby-processing

Hackety Hack - http://hackety.com/