CVS, GIT, and Mercurial as well as other well-known version control systems cannot version directories. In other words, you cannot add empty directories. A "workaround" for this issue is to use placeholder files that are placed into empty directories. These placeholder files can then be committed into the repository and will make sure that, upon checkout, the directory tree is entirely reconstructed. The problem with using placeholder files is that you need to create them, and need to delete them if they are not necessary anymore (because sub-directories or real files were added). With big source trees, managing these placeholder files can be cumbersome and error prone. MarkEmptyDirs can manage the creation/deletion of such placeholder files automatically. It creates placeholder files in all empty "leaf" directories. If later on new files or directories are put into such directories, the placeholder files are not necessary anymore, and are removed automatically.
Meld is a visual diff and merge tool. It integrates with most version control systems. The diff viewer lets you edit files in place (diffs update dynamically), and a middle column shows detailed changes and allows merges. The margins show location of changes for easy browsing, and it also features a tabbed interface that allows you to open many diffs at once.
RepoManager offers a minimalistic approach to Web-based management of version control system repositories. Its goal is to simplify effective handling of repository permissions for a large number of users. Using RepoManager, users themselves are able to grant others permissions to use their repositories whenever they want.
Submin provides a Web-based admin interface to your Subversion repositories. Its features include user/group management, path permission management, and the ability to create svn repositories. It uses htpasswd/svn authz for authentication, so it can use the same login information as apache2/svn (and trac). It works with FF3, IE7, Safari 3, Chrome, and Opera 9.
TurnKey Revision Control Appliance is an integrated revision control server combining the best open source version control systems: Subversion, Git, Bazaar, and Mercurial. A Web interface is included for each system, making it easy to browse through the code base, compare revisions, and manage repositories for multiple projects. No configuration is required and security patches are automatically installed. A Web management interface, configuration console, and AJAX Web shell are provided. To minimize footprint the appliance is built from the ground up with the minimum required components. It runs everywhere thanks to multiple build formats, including an installable live CD, a VMDK with OVF support, and an Amazon EC2 AMI.