I received an e-mail asking me how I got started with OpenBSD, so I thought I'd write the answer here in case anyone else wanted to read it.
I started using OpenBSD in 1998 (version 2.3 or 2.4) to host a BBS that I was running. I chose OpenBSD because of its security record and because I was getting fed up with Linux (Slackware) at the time. I think the machine was a Pentium 75 or something, and OpenBSD worked quite well on it. During the course of building the BBS, I had to install some 3rd party software, so I got interested in OpenBSD's ports system to make installation of that software cleaner. I submitted some ports to the ports@ mailing list and got them committed by other developers. I tested others' ports and supplied feedback where I could. I hadn't done much unix development back then, so writing simple makefiles for ports was an easy way to get involved.