A web-based interface to a CVS tree, developed by the Mozilla project and released as open source under the NPL and MPL licenses.
It allows you to perform various queries on a tree. For instance, it allows you to find out which tree checkins were made between two dates, or the differences between different revisions of a file.
It is implemented as a CGI script written in perl, uses a MySQL backend to store information which speeds up queries, and requires read access to the CVS repository and e-mail notification of all changes.
It is used by many popular open source projects, including GNOME, AbiWord and Mozilla.