I joined Wikipedia in November 2002, following an outage at my previous outlet for writing: h2g2. I rapidly realised that Wikipedia's system corrected problems that were preventing h2g2 from achieving its stated goal, and moved over quite quickly. Initially I copied across content I'd written for h2g2, such as articles on Luke Rhinehart and gender-neutral pronouns, before branching out into other areas, notably around gender and religion. I also spent time trying to broker agreements on the never-ending Israel vs Palestine edit war, and other contentious subjects.
Over time I became involved with policy discussions, became an administrator, and was appointed as an arbitrator in 2004. I'm glad that some of the policy elements I introduced or championed have become healthy and productive parts of Wikipedia. These include:
Of course, in doing so I contributed to the ongoing problem of instruction creep, so it wasn't all positive.
I left around February 2005, though I have made occasional edits since then. I am thankful for the things I've learnt from Wikipedia, both factual and social. I am glad I was part of something that is now so useful to so many people. I regret those problems with Wikipedia that still persist, and hope they will be resolved.