gloox is a portable high-level Jabber/XMPP library for C++. It is fully compliant with the XMPP RFCs, supports all of the XMPP features (including SRV lookups, TLS, SASL, roster management, and privacy lists), and implements several XEPs that make it ideal for writing any kind of Jabber/XMPP client or component.
GluX is a cross-platform, easy-to-use OpenGL extension loader. It offers a very simple mechanism for loading and using OpenGL extensions. It allows your code to compile under Windows and Linux even if your video card doesn't support the OpenGL extensions used by your program. At run time, gluX will detect if required extensions are present or not.
gnokii is a multisystem tool suite for mobile phones. It provides a library to communicate with a phone hiding the communication protocol. The library handles SMS, phonebook, calendar, phone calls, and other mobile phone capabilities. It supports Nokia-FBUS mobiles, AT-capable phones (most of the mobiles), as well as Symbian-based phones.
gnuboy emulates the Color GameBoy handheld console in portable C, with interfaces for X11, Linux fbcon and svgalib, SDL, DOS, and Windows, with other ports planned in the future. Compatibility with ROMs tested is around 99 percent, and all major hardware features except SGB extensions are supported. With the optional optimized i386 assembly code, gnuboy can run at the full 60 FPS even on Pentium/75s and below. No special libraries are required to compile, and gnuboy is known to build on many *nix variants.