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.
Boar provides simple version control and backup for photos, videos, and other binary files. Boar aims to be the perfect way to make sure your most important digital information, like pictures, movies, and documents, is stored safely. It makes it possible for you to restore any or all of your files from any point in time. It makes it easy to maintain verified backups of your data, including file history. It imposes no limits on file or repository sizes. Using boar is an effective way to prevent data loss due to human or machine error.
eacc is a bash script that allows a group of people to share an encrypted, revision controlled file on a shared filesystem. Rather than store an encrypted file in RCS, eacc encrypts the RCS file and handles the decryption, check-out, check-in, and encryption steps automatically. The repository is encrypted using GPG's multi-recipient support, which allows each member of the group to use their own unique password. A typical use case would be to securely store sensitive information, such as password lists or account information, that is shared by a team.
Hgfs is a read-only filesystem interface to Mercurial repositories. The interface gives access to the commit message, manifest, and files of each revision, and to .tgz's of each revision (the .tgz's are generated as they are read). The filesystem is a front-end for the Mercurial library that comes with it. All code is written in Limbo, for Inferno.
irked is an IRC client that runs as a daemon accepting notification requests as JSON objects presented to a listening socket. It is meant to be used by hook scripts in version-control repositories, allowing them to send commit notifications to project IRC channels. A hook script that works with git, hg, and svn is included in the distribution.