I first released Autodia back in late 2000, it's a fairly small project, doing a specific and small job of interest to some programmers.
I remember how pleased I was the first time somebody emailed me about it, saying thanks and how useful it was. It was a huge surprise and I was really chuffed, that somebody the other side of the world (I think it was South America), had found it and thought to contact me.
Nearly 10 years later it's almost an every day thing. The number of contributors is now just under 50, with another 20 or so bug reporters.
All that for a pretty simple tool that has no mailing list, a couple of (unfortunately out of date) web pages, and only had public version control since last year.
I put almost no effort at all into publicising it, releases are infrequent and the website needs work - but still people find it, post patches and test cases and even sometimes just say thank you without requesting a bug fix.