Larger software projects I work on:

FreeBSD

FreeBSD is an OpenSource implementation of a complete UNIX-compatible operating system. It contains everything you need for a running system, including kernel, C libraries, commandline tools, installation program and a superb system to integrate and update third-party applications.

This page gives an overview on some of the outstanding features.

CMU Common Lisp
The CMU implementation of the Common Lisp programming language.

Software of my own:

cstream
cstream is a dd(1) replacement and general streaming commandline tool. cstream has its own homepage.

shellsupport
shellsupport(1) is a commandline utility that implements those functionality I most often miss when writing shellscripts.

shellsupport has its own homepage.

ledbiff
ledbiff is a simple program that switches LEDs on the keyboard when mail arrives. For now, it is X11 only, but I plan to extend it to pcvt, syscons and the Linux console.

Usage:
  -f <file>    Monitor file <file>.  If not given, tries to determine 
               main mailbox for the current user.
  -l <n>       Use LED number <n>.  Note that in XFree86 the leftmost
               LED is number 2, not 1.
  -s <n>       Sleep time between checking the file.

cratimeout
cratimeout is a wrapper about commandlines. As the namesuggests, after a specified timeout the commandline will terminate.

cratime has been coded carefully to change the semantics of the called program as few as possible. In particular, it preserves signal behavior. SIGINT, SIGQUIT etc. sent to the program will make the whole commandline have the signal semantics as if the program was called directly.

ICSPLL
ICSPLL is a set of tools to mess with chipsets.

For now I have tools to real the digital core temperature sensors on modern Intel CPUs (Core2 architcture - Conroe, Woodcrest, Clovertown etc.) and to display and change memory timings on 975x, 965 and 5000x chipsets (5000x view only).