gitty-gitty, the (general | GNU) template generation tools, are a set of scripts for creating a whole set of sources which may already be compiled and installed using the GNU development tools. Think of gtgt as a program which is able to create an already compilable, very sophisticated "hello world" program, written in C or C++ and constituted by a main program, two internal modules (classes), and one static and one shared library, and this complex "Hello World" is already fully embedded into the GNU autoconf/automake development environment. By using gitty-gitty, you will get a template of sources for the main cases you might meet, and which you can also use as examples for automake, autoconf, etc.
GKrellM is a GTK-based stacked monitor program that charts SMP CPUs, disks, load, active net interfaces, and internet connections. There are also builtin monitors for memory and swap, file systems with mount/umount feature, mailbox checking including POP3 and IMAP, clock/calendar, laptop battery, sensors (temperatures, voltages, and fans), and uptime. It has LEDs for the net monitors and an on/off button and online timer for PPP. There is a GUI popup for configuration, plugin extensions can be installed, and many themes are available. It also features a client/server monitoring capability.
GLAME (GNU/Linux Audio Mechanics) is meant to be the GIMP of audio processing. It is designed to be a powerful, fast, stable, and easily extensible sound editor for Linux and compatible systems. It has full support for non-destructive editing including undo/redo and applying LADSPA effects. Its supported platforms are Linux, BSD, IRIX, and OS X. It uses guile and libxml, and the GNOME libs available is highly recommended. MP3 and Ogg files can be processed if libmad and libvorbisfile are installed.