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.
The scale-invariant feature transform is an algorithm to identify and locate interesting points within an image. For all such points, a descriptive signature is extracted. The signatures can be stored and matched among multiple images, allowing for a large number of interesting applications, such as aligning overlapping images and identifying objects or motion within image sequences. libsift is used by the autopano-sift program to create panorama images.
Wieldy is a to-do list manager that is based on the principles of GTD (Getting Things Done). It allows you to manage your to-dos in a simple but effective way. To-dos can be created as thoughts and actions, which can then be assigned to the Next Action, Today, or Someday categories. Tasks can also be scheduled and listed in a calender-like overview, as well as linked to a project or simply put on hold. Wieldy also allows you to manage your contacts and delegate actions to them. Other features include support for data encryption, tagging, priorities, recurring action templates, and synchronization with other PIMs like Outlook. No installation is needed.
Af-Arch is an N-tier development framework to quickly build high-quality distributed applications. It currently supports C and C# programming languages, which enables you to write client applications using them. It currently runs on GNU/Linux and Microsoft Windows, and is being used in production environments.