gitolite is an access control layer on top of git. It allows you to setup git hosting on a central server, and have multiple "virtual" users (i.e., not "Unix" users) access multiple git repositories, with fine grained access control (read control at the repo level granularity, write control at branch/tag/file/dir level). It has several other features, comprehensive documentation, does not require root permissions, and does not depend on anything except git, Perl 5.8 or later, and any POSIX shell.
Diffuse is a graphical tool for comparing and merging text files. It can work with many revision control systems as a diff viewer or merge tool. Diffuse is able to compare an arbitrary number of files side-by-side (n-way merge), and gives the user the ability to manually correct line matching and directly edit the files.
Chora is built upon the Horde Application Framework and provides a read-only browser interface to any number of version control repositories. Advanced features include a visual branch view of the repository's history, pretty-printed output, annotation, patchsets and basic statistics.
svnauthcheck checks the syntax of a subversion authorization file and generates Apache-like permission specifications to be used by other tools such as ViewVC. svnauthcheck, in combination with subversion pre- and post-commit hooks, can be used to delegate the administration of a repository authorization to the end users.