DocBox: Wiki-Like Ruby / Rails Documentation For Everyone
DocBox is the latest attempt to improve the Ruby/Rails documentation scene. Created as a Google Summer of Code project by Ian Ownbey (mentored by Jeremy McAnally) DocBox "sits on top of RDoc and allows users to update documentation through a wiki-like interface." Changes to the 'wiki' are then folded back into your code and committed to a git documentation branch.
While still young, this project shows a lot of promise, as it allows anyone to write detailed, versioned, documentation without having to download or view any source code.