Galaxy Games Online (GGO) is a role-playing game (RPG), text-based, online game playing tool. It includes fully featured text chat, online/offline capabilities, dynamic character sheets, powerful statistics, an integrated programming language, and much more. It's free to use, and comes with a comprehensive help file and sample character sheets.
For more information see the old GGO home page at http://ggo.jevon.org/
Note now that the software is pretty much abandoned. It would need a rewrite (it's currently in Visual Basic
6) to be useful again in the future.