Amiga Mach: A port of the Mach 3.0 microkernel to the Amiga, which is how I got into Mach (and microkernels) in the first place. This was the first fully non-proprietary 680x0 port. Unfortunately, the project sort of fizzled after we got the microkernel running reliably, because there was no usable, freely available Unix server.
XPK (eXternal PacKer): A cooperating set of programs for the Amiga together comprising a complete data compression system. XPK allows many different compression algorithms to be used transparently by many different applications, through a standard master library. The master library provides a convenient high-level interface to applications, and at the same time, offloads most of the grungy administrative tasks themselves from the actual algorithms implementing compression. Many people have contributed compression algorithms, applications, drivers, and other components to the XPK system, and it has become a de facto standard for many aspects of data compression on the Amiga. My part in the project was in the design of the master library and one of the first compression libraries (a form of the well-known LZW algorithm). The complete XPK system can be gotten from ftp.wustl.edu or any other aminet FTP site.
Chroma Paint: A full-featured commercial paint program for the Amiga I wrote years ago and marketed through a small company in Logan, Utah. Didn't sell real well, but it was a fun experience.