Free software projects I've worked on or otherwise contributed code, fixes, testing, or other significant resources to:
VMD
NAMD
OpenBSD
Mesa
FreeVR
VRPN
FLTK
NetBSD
Network UPS Tools
FlightGear
cvs2html
OpenAL
POV-Ray (and its predecessor DKBtrace)
MpegTV
(VideoCD testing)