Sad or not, my greatest contribution (so far anyhow) to the open source world has been as a proofreader.
Which is why I'm digging git now. I can fork the project, fix the typos, and send a pull request.
I have no idea how to do the equivalent for subversion (which would probably be, generate a patch and submit a bug report with the patch attached).
So yay, git!
(Note: enthusiasm can be applied to any DVCS system.)