Manage 100 branches.
Create 10 repos with 10 branches each, 2 changes per branch to one of 10 random files (0-10).
Then turn the bookmarks into namespaced bookmarks, because FelipeC thinks that necessary for managing branches.
Reason: Take the challenge: http://felipec.wordpress.com/2011/01/16/mercurial-vs-git-its-all-in-the-branches/
Run it with python test.py. Then cd into mine and use
$ hg bookmarks
it gives you the list of namespaced bookmarks
For rebasing just use
$ hg rebase -d [name of the bookmark]