I've written one small open source library, which I publicized a little bit back when I first released it. Like you said, I wrote it mostly to scratch my own itch, but it was really nice to see it get some use out in the wild, and I have gotten a few emails about it over the years. Personally, I really enjoy getting any kind of emails about it from people who are using it or who have questions. (To be fair, I've never gotten the murdery emails abou it)