Bonsaï is tree control

It is a tool that lets you perform queries on the contents of a CVS archive; you can:

get a list of checkins,
see what checkins have been made
- by a given person,
- on a given CVS branch,
- in a particular time period.
It also includes tools for looking at checkin logs (and comments); doing diffs between various versions of a file; and finding out which person is responsible for changing a particular line of code ("cvsblame").