Ved (visual editor) is a small and very fast screen-oriented text editor that implements a user interface somewhere between vi and Emacs. It is powerful and easy to learn, and has no limitations on line length, file size, or the types of characters that may appear in a file. It is a highly portable editor for Unix and most other OSes.
BRL-CAD is a powerful constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing support for rendering and geometric analysis, path-tracing for realistic image synthesis, network distributed framebuffer support, and image and signal-processing tools.
fli4l is a single-floppy Linux-based ISDN/DSL/ethernet-router. It features configuration with some simple ASCII-files, several possible connection-flavors (in/out/callback, and raw IP/PPP), channel bundling (an extra channel can be added through a Windows/Unix-client), configuration of multiple networks, least-cost routing, automatic choice of provider, display/calculation of connection times and costs, and a Windows/Unix client to control dial/hangup, monitor traffic and monitor incoming calls on ISDN (see screenshot).
WorldStation is a Java-based control panel to control the Ten-Tec DSP RX-320 shortwave receiver. The RX-320 is a "black box" radio which has no front-panel and is controlled via your PC's serial port. With an appropriate antenna, the RX-320 will allow you to listen to thousands of broadcasts from around the world. WorldStation features integrated Xbase frequency database support and advanced scanning to allow the user to visualize the radio spectrum.
MPlayer is a movie and animation player that supports a wide range of codecs and file formats, including MPEG 1/2/4, DivX 3/4/5, Windows Media 7/8/9, RealAudio/Video up to 9, Quicktime 5/6, and Vivo 1/2. It has many MMX/SSE(2)/3Dnow(Ex) optimized native audio and video codecs, but allows using XAnim's and RealPlayer's binary codec plugins, and Win32 codec DLLs. It has basic VCD/DVD playback functionality, including DVD subtitles, but supports many text-based subtitle formats too. For video output, nearly every existing interface is supported. It's also able to convert any supported files to raw/divx/mpeg4 AVI (pcm/mp3 audio), and even video grabbing from V4L devices.