Here's a list of some free / open source software I have written over the years. Enjoy!
A C++ library that generates invertible constant-Q spectrograms. See the Gaborator home page.
A simple tool for generating printable call graphs of C programs. See the egypt home page.
A 96 kilobit/s DSL softmodem for BSD/Linux systems, using PC sound cards as the line interface. See the AuDSL home page.
A network Mandelbrot program. See the MandelSpawn home page.
This obfuscated anagram program won the award for "most humourous output" in the 1992 International Obfuscated C Code Contest. It's not only highly obscure C code, it's also one of the fastest anagram programs on the planet. It is available by HTTP from this server as two separate files: the source code file gson.c (all 1513 bytes of it) and the documentation file file gson.hint.
AG is now also available as an app for the iPhone and iPod Touch.
An interpreter for the CHIP-8 video game virtual machine language running on the HP48SX pocket calculator. The original CHIP-48 distribution is available by FTP in ftp.funet.fi:/pub/misc/hp48sx/chip/chip48-2.25-bin. The same directory also contains an enhanced CHIP interpreter called SCHIP and other related software.