I have a counter-example. I built an OSX application for remotely tailing logs on servers (http://www.remotetailapp.com/). Originally I did it to scratch and itch when I was administering a bunch of servers over SSH. I added Heroku log support when I started working on a Heroku project. I had dreams that it might grow into a self-sustaining side project, but it hasn't really taken off. The key lesson that I learnt is that the technology just solves part of the problem. Just because it is downloadable software rather than SaaS doesn't mean that you don't need to put effort into marketing and sales.