Darning is a tool for managing a series or sequence of patches to a software source tree, in the same vein as quilt but with extended functionality. It supports advanced patch concepts such as file mode changes and copying/renaming files. The GUI is the primary interface and the most complete, but a command line interface is also provided with fewer features at this stage.
audioloader is a minimalist music library browser that enables the browsing of a local music collection in any Web browser. It supports album/directory oriented audio/music listening. Album playlists are generated dynamically, and can either be queued into Audacious through a script distributed with the application or downloaded and opened with any music player. It is self-contained with no dependency on any external application but the Web browser, and supports cover art display, history, random album selection, and sub-collections. It has limited mobile support, as well.
A lot of stereoscopic cameras use the .MPO format to store two JPEG images, including the Fuji W1, W3, and a few 3D camcorders that have a still mode. It can do two things for you: it can separate out the image files into a left and right pair, so you can process them or do whatever you want with them, or it can create an anaglyphic image (the ones you need coloured glasses to view). It is simple to use from the command line and takes wildcards, so you could process a whole batch of files with: mungempo *.MPO.
mdepub is a tool that allows you to compose a book in Markdown format and use Pandoc and Calibre to compile an Epub package including all of the book's source material. In effect, you can keep the source and product in the same file in your library; if you ever want to revise the product, you merely need to extract the source, make edits, and recompile.
CrutziPlayer is a standalone player for NPAPI-based browser plugins (e.g., Flash). It provides external, hardware accelerated fullscreen scaling using XComposite, Cairo, and XFixes. It's a good solution, for example, for playing browser games fullscreen on Linux, as it autodetects the original .swf content size.
pyscmpd is a music player daemon designed for use on Raspberry Pis. It implements a subset of the MPD protocol, but instead of serving local MP3 files, it connects to SoundCloud.com and serves the streams found there. It supports a huge number of front-end clients through MPD, including ncmpcpp and Sonata. It allows you to configure which parts of SoundCloud are made available for browsing by defining categories and adding groups or users to them.