I was looking around for a solid issue tracking system, written using Ruby on Rails. There are some good comparisons on wikipedia. Redmine seems like a good choice; all the standard functionality, that you would expect from a issue tracking system, is available. For instance:-

• Raising Bugs/Defects
• Request Features
• Adding Patches
• Roadmaps
• Forums
• Wiki
• Code Repository

The code repository can use the source control apps, Git and Subversion.

All in all, a pretty solid choice.