Per memory, my earliest contribution to open-source was in 1996 (link).

These days my open-source work is mostly at the Elftoolchain project (which is hosted at SourceForge.Net currently).  Apart from Elftoolchain work, I am a committer at the FreeBSD & NetBSD open-source operating system projects.

My *BSD related open-source work is browseable the FreshBSD.org tracker site.