MLton is a whole-program optimizing Standard ML compiler. It generates standalone executables with excellent runtime performance, supports the full SML 97 language, and has a complete basis library. It also has a fast C FFI, source-level time and allocation profiling, and many useful libraries.
Red-Piranha is a search system that can actually learn what you are looking for. It can be used as a Web page, command line, or XML-WebService, so it will work with most languages, including Java, Perl, C#/.NET, and PHP. It includes learning abilities for the Desktop/Internet search functionality. All feedback from the user is stored in (editable) XML and RDF, and is used by the system to improve the quality of searches.
HATop is an interactive ncurses client and real-time monitoring and statistics displaying tool for the HAProxy TCP/HTTP load balancer. HATop's appearance is similar to top(1). It supports various modes for detailed statistics of all configured proxies and services in near real-time. In addition, it features an interactive CLI for the HAProxy Unix socket. This allows administrators to control the given HAProxy instance (change server weight, put servers into maintenance mode, etc.) directly out of HATop (using keybinds or the CLI) and monitor the results immediately.
Mr. Voice is a specific-purpose Perl/Tk front-end for an MP3 database. It was written to provide an easy-to-use MP3 solution for the production booth of an improv comedy troupe, and as such is tailored to providing quick searches and playback of MP3s that are split up into categories. While not intended to be a standalone desktop MP3 player, others in a similar situation may find it useful.
Infinity is a visualization plugin with light effects originally written for XMMS and now ported to Audacious. It supports full-screen mode, mouse resizing, and saved preferences. It is designed to be as end-user oriented as possible, so installation and manipulation are kept simple. It requires SDL and GTK+ 2.0 to run, and doesn't require 3D acceleration support.
Verona is a portable VOIP toolkit based on eXosip, oSIP, oRTP, curl, and ffmpeg. The toolkit includes a phApi module, which is a high level VOIP API that allows a developer to create voice/video over IP applications in a dozen lines of code. It includes an example of a minimalistic SIP user agent that supports audio and video transmission. The toolkit is basically the VOIP engine used by the openwengo project.