Miscellaneous software that does not fit in other categories...
OpenGL/FreeType is a simple engine for displaying a unicode text using a (single) vertex buffer. The idea is simply to tightly pack every necessary glyphs into a single texture and to generate a single vertex buffer to draw the text.
Inspired by the wordle site, I made a quick try in python using cairo, numpy and pyglet to get more or less the same result. The script allows you to save the image as well as a clickable map to link each word to a specific link. Code can be improved in a lot of different ways so feel free to modify it.
Hills screensaver let you gently drift over rolling grassy hills, using ARB multitexture, heightmap and lightmap. It requires SDL and OpenGL and should work with xscreensaver and gnome-screensaver.
Chris Kent has ported hills to OSX and made a screensaver out of it (sources). Nick Ziztmann has since released an updated version on http://seiryu.home.comcast.net/~seiryu/savers.html and sources are available on github.
GNUBiff is a mail notification program that checks for mail and displays headers when new mail has arrived. GNUbiff features include multiple mailbox support, pop3, apop, imap4, mh, qmail and mailfile support, SSL & certificates support, GNOME & GTK support and many other features.