As a Mercurial user, our project uses clones as branches. So our project is using hg/repositories/unstable and hg/repositories/0.3, etc.
Would be really nice if one project could carry/manage/handle multiple repositories, sharing the same set of tickets.
If you implemented this, you'd have a feature which none of the competition has yet. :)
This is a great feature request, I will start on this when I get to the repository browser.