libefgy is a set of C++ headers containing lots of templates loosely related to maths. The headers include templates for fractional arithmetic, big integers (and thus "big fractions"), calculating π, e, and some calculations with those (for trigonometrics), matrix manipulations, tuples, polar and Euclidian spaces in arbitrary dimensions, (perspective) projections, colour space manipulations in RGB and HSL, and assorted other things.
ZShaolin installs a powerful terminal on your Android device, without requiring root. It comes with applications to edit text, images, audio, and video using shell scripts and programs like FFMpeg, ImageMagick, Sox, Oggz, Lua, awk, sed, vim, emacs, git, SSH, and rsync. A zsh command line environment comes pre-configured with colors, smart completion, error correction, and all man pages, making ZShaolin also suitable for those who would like to learn shell scripting and Unix system administration via a remote session.
Cairo is a vector graphics library with cross-device output support. It currently supports the X Window System and in-memory image buffers as output targets. It is designed to produce identical output on all output media while taking advantage of display hardware acceleration when available (eg. through the X Render Extension). It provides a stateful user-level API with capabilities similar to the PDF 1.4 imaging model and provides operations including stroking and filling Bezier cubic splines, transforming and compositing translucent images, and antialiased text rendering.
Twisted is an event-based framework for Internet applications. It includes a Web server, an SMTP/POP3 server, a telnet server, an SSH server, an IRC server, a DNS server, a generic client/server pair for remote object access (Perspective Broker), and APIs for creating new protocols. It supports integration with GTK+, GTK+ 2, Qt, Tkinter, wxPython, Mac OS X (PyObjC) and Win32 event loops. It also supports TCP, SSL and TLS, UDP, Unix sockets, multicast, and serial ports. Supported protocols include HTTP, FTP, SMTP, POP3, IMAP, TOC, OSCAR (AIM and ICQ), SSH, DNS, IRC, NNTP, Jabber, SOCKSv4, Telnet, SIP (for VoIP), and XML-RPC and SOAP using external packages. Most protocols are supported as both servers and clients.
X11, or X, is a vendor-neutral, system-architecture neutral network-transparent window system and user interface standard. In other words, it's a GUI for UNIX. X can use your network -- you may run CPU-intensive programs on high powered workstations and display the user interface (the windows) on inexpensive desktop machines.
pyratemp is probably (one of) the smallest complete template-engines for Python (with about 500 LOC). It has a very small set of special syntax in the templates. This reduces complexity and the probability of bugs and lead to an easy-to-use and intuitive user-interface. It uses embedded Python-expressions (in a "sandbox"), is well documented, has full Unicode-support, and produces very good error-messages, which is very useful when creating new templates.
Popt is a C library for parsing command line parameters. Popt was heavily influenced by the getopt() and getopt_long() functions, but it improves on them by allowing more powerful argument expansion. Popt can parse arbitrary argv style arrays and automatically set variables based on command line arguments. Popt allows command line arguments to be aliased via configuration files and includes utility functions for parsing arbitrary strings into argv arrays using shell-like rules.