Ditz is a little (ruby) gem I ran into today. It allows every developer to maintain their own issue tracking database, saved in human readable YAML files, which can be easily exchanged along with the corresponding code changes through a distributed version control system, such as git.

As the latest version number, 0.4, implies, ditz is still at an early stage, but the idea of distributed issue tracking and managing the issues themselves as part of the codebase sounds very interesting to me.