Thunderbird is a total redesign of the Mozilla mail component to produce a cross-platform, stand-alone mail application using the XUL user interface language. It has many new features, among them the ability to customize your toolbars the way you want them. a new look and feel with a large number of downloadable themes which alter the appearance of the client, and the ability to add UI extensions.
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.
CUPS is a standards-based printing system for Mac OS X and other Unix-like operating systems. It provides the System V and Berkeley command line interfaces, and uses the Internet Printing Protocol ("IPP") as the basis for managing print jobs and queues. The Line Printer Daemon (LPD) Server Message Block (SMB), and AppSocket (a.k.a. JetDirect) protocols are also supported with reduced functionality. CUPS adds network printer browsing and PostScript Printer Description ("PPD") based printing options to support real world printing.
KeyBox is a Web-based SSH console for executing commands and managing multiple systems simultaneously. It allows you to share terminal commands and upload files to all your systems. Once the sessions have been opened you can select a single system or any combination on which to run your commands. Also, additional system administrators can be added and their terminal sessions and history can be audited.
Wine is an implementation of the Windows API on top of X and Unix. It does not require Microsoft Windows, but can use native Windows DLLs if they are available. It provides both a development toolkit for porting Windows source code to Unix as well as a program loader, allowing many unmodified Windows programs to run on x86-based Unixes.
Concurrency Kit provides a plethora of concurrency primitives and lock-less and lock-free data structures designed to aid in the design and implementation of high performance scalable concurrent systems. It was designed to minimize dependencies on operating system-specific interfaces, and most of the interface relies only on a strict subset of the standard library and more popular compiler extensions.