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.
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.