If you're a developer of multiple projects, you'll find yourself needing to switch between multiple different version control systems. After working in one (e.g. SVN) for an hour, you may need to switch to a different one (e.g. git). Getting your fingers to switch is the difficult part, or remembering the right command line flags to use for the given tool. That's where The One Ring comes in: it provides a constant interface to all the version control systems, and your fingers only need to remember a single command regardless of what checkout directory your shell is sitting in.
geh is a simple command line image viewer with various nice features. It currently supports a slide-show mode displaying multiple images in a row either controlled by a time interval and/or mouse button clicks, and a thumbnail mode creating small thumbnail images and caching them in ~/.thumbnails according to freedesktop.org's thumbnail specification.
pyvm3 is a hobby project that's based on a compact virtual machine that can run Python bytecode and supports classic Python and whitespaceless Python frontends. On top of this there are implementations of various applications like a Web browser, PDF viewer, font rasterizer, SSH, PGP, a windowing environment on linuxfb, a video/MP3 player, and more.
FreeSentral is an easy-to-use IP PBX based on the telephony engine Yate. Some of its features include call forward, extension groups, call logs, call hunt, call hold, Auto Attendant, call pick up, call transfer, conference, and voicemail. The demo offers a glance into how FreeSentral works. A wizard assists users on their first configuration of the IP PBX.
WikiPBX is a PBX Web interface for FreeSWITCH. Multiple "accounts" are supported per server instance: each account is effectively a completely independent PBX. Configuration is layered so that XML files go on top of what is stored in the database. This allows you to use a database, but stays out of your way if you choose to use flat files. Extensions, SIP endpoints, and gateways can be configured via a Web interface. Live calls can be viewed, hanged up, and transferred. Call history (CDR records) can be viewed over the Web interface. There is a Web interface for managing IVRs. "Sound clips" can be easily recorded for use in dialplan or IVRs. Audio or text-to-speech can be injected into live calls.
MoCo is a system that monitors and controls SCADA points, such as temperature, HVAC, power, lighting, sprinkler systems, and more. It has industrial capabilities, but is scalable from very small home systems to enterprise, world-wide ones. It works with inexpensive I/O bridges (including X10, Insteon, and 1-wire) from a number of manufacturers. It has sophisticated history logging and diverse control capabilities, as well as a 117-page implementation manual.