I’ve made a few small contributions to the free software community.
I contributed the PAM support for Masqdialer. PAM stands for Pluggable Authentication Modules, and is the system used for authentication by many Linux distributions (such as Debian and RedHat) and Solaris.
The R project develops a statistical computing system called R. R is an amazing piece of software, and is probably the best available tool for producing graphs suitable for scientific publication. Back in 1999 I wrote a graphical user interface for R, using the GNOME libraries.