I've been enjoying contributing what little I can to the software projects I use.
When I had a C++ programming class, I used a nifty site that provided lots of reference documentation. Unfortunately, some of the documentation was incorrect. I told them about it, and they not only fixed the problem, but mentioned me in their list of contributors!
Now I'm using Drivel to post to this blog, and I discovered that it was generating malformed HTML. I realized the fix would be trivial, so I made the changes and posted a bug report along with a patch to fix it. I don't know if Drivel has a list of contributors, but it feels good to be able to contribute and give back to the community. Hopefully I'll have an opportunity to continue contributing (usefully!) to the software.