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.
The Simple Sockets Library makes sockets easy to use and comes as public domain source code. It resembles C's file I/O, uses whatever port is available, has named servers and port reuse, streaming/blocking sockets used, polling support, blocking/selection support via numerous functions, timeout control and firewall support.
XCmail is a MIME and multi POP3 capable mailtool for X11 using the Xclasses X11 layout library. Its main purpose is to read and write mail, allowing any kind of data to be attached. It can handle MIME types, has helpers to show different types, and can encode and decode binary data into ASCII to allow it to be transported as mail over the Internet. It has many built-in functions such as 2 vCards, unlimited POP3 servers, SMTP, SMTP after POP3, SMTP-AUTH (RFC2554), addressbook, encoders, filters, a special spam filter, spell checker, xface, and a new "virtual folder" concept. It also uses external programs to enhance its feature set. XCmail can be extended through a plugin interface.
The ANSI/ISO C++ specifcation includes a standard C++ library, also known as the STL. GCC by default comes with an implementation that does not comply with this standard, but instead partly implements an older version. STLport is a freely available implementation, based on the SGI STL implementation. It is fully-compliant, supported, and very fast. It includes special debugging facilities and interesting and useful extensions to the standard.
Mp3Kult is an application for KDE 3. It organizes your MP3/Ogg collection in a MySQL database. It can read MP3/Ogg tags and song information (length, bit rate, sample rate, etc.), make playlists, play songs with an external player (xmms, gqmpeg), find a song in database (base and advanced search), and make a copy of a playlist on your hard disk (to play the playlist without inserting CDROMs). Mp3Kult can recursivly scan directories to find MP3/Ogg files, and it can automatically mount, umount, and eject a CDROM before/after a job.