Genius is an arbitrary precision integer and multiple precision floating point calculator. It includes its own programming language similar in some aspects to C, bc, or Pascal. It can deal with rational numbers and complex numbers. It has matrix support as well. It uses the gmp library so it is very fast for calculations of large numbers. It has a command line and a GNOME interface. The GNOME interface supports plotting functions and 3D surfaces.
gtex-letter attempts to deliver an easy alternative interface to LaTeX-letter. It is heavily configurable, and it supports multiple letter headers and default letter openings (which are configurable in the rc-file). Users can choose from three different levels of graphical interface complexity. Novice is easy to understand, while expert is straight-forward. There is also a non-interactive mode that makes production of standard-letters very fast. gtex-letter is implemented in Python and based on GNOME.
lookuplet is a GNOME utility that allows you to easily enter search terms (it automatically grabs the X selection when invoked) and then press a key combination which will cause those terms to be substituted into a URL which is launched using your preferred Web browser, or to be substituted into a command line which is invoked. It is rather useful for things like dictionary lookups, Web searches, map lookups, etc. The idea is to shave seconds off of queries that you find yourself doing all of the time. Though it uses the GNOME libraries, it doesn't require that you be running the GNOME desktop environment.
Gemu is a Gnome application designed to configure sound cards based on the EMU10K1 platform from Creative Labs. Gemu is capable of adding, viewing and deleting audio routes, turning on Live Drive IR, turning on the 12db boost to the front/headphone jacks on Live cards, setting the S/PDIF frequency on Audigy cards, setting the recording source, turning on digital passthrough mode, setting to the analog or digital mode of the dual-mode jack of 5.1 cards, adding and seeing patches for sources and destinations, and controlling volume on a per-route basis or by source or destination.