getmail is intended as a simple, secure, and reliable replacement for fetchmail. It retrieves email (either all messages, or only unread messages) from one or more POP3, SPDS, or IMAP4 servers (with or without SSL) for one or more email accounts, and reliably delivers into qmail-style Maildirs, mboxrd files, or through external MDAs (command deliveries) specified on a per-account basis. getmail also has excellent support for domain (multidrop) mailboxes, including delivering messages to different users or destinations based on the envelope recipient address.
Gentoo Linux is a versatile and fast Linux distribution for x86, PowerPC, Sparc, and Sparc64 that's geared towards Linux power users. Unlike other distros, it has an advanced package management system called Portage. Portage is a true ports system in the tradition of BSD ports, but is Python-based and sports a number of advanced features including dependencies, fine-grained package management, "fake" (OpenBSD-style) installs, path sandboxing, safe unmerging, system profiles, virtual packages, config file management, and more.
Allegro is a multi-platform game library for C/C++ developers that provides many functions for graphics, sounds, player input (keyboard, mouse, and joystick), and timers. It also provides fixed and floating point mathematical functions, 3D functions, file management functions, compressed datafile, and a GUI.
Librep is a shared library implementing a Lisp dialect that is lightweight, reasonably fast, and highly extensible. It contains an interpreter, byte-code compiler, and virtual machine. Applications may use the interpreter as an extension language, or it may be used for standalone scripts. Rep was originally inspired by Emacs Lisp. However one of the main deficiencies of elisp--the reliance on dynamic scope--has been removed. Also, rep only has a single namespace for symbols.
The GNU Gatekeeper is a free H.323 gatekeeper based on the OpenH323 project. You can use it to manage a Voice-over-IP network and let endpoints (e.g., Netmeeting) communicate through symbolic names. It also has an external interface for billing and other applications. It runs on a number of Unix versions (including Linux and Solaris) and Windows.