One of my very first projects that actually made it to real users was Skivsamlingen, developed in the dawn of my PHP days. Skivsamlingen means The Record Collection, and is not surprisingly a web application where users can list all their records.
The size of the target group has admittedly decreased somewhat since the era of iTunes, Spotify and Grooveshark, among others, begun, but there are still active users on the site. These users are the reason I felt I had to clear my conscience for barely working on the site for many years. Possible solutions are to make time for the site, take it down, or simply make other people work on it.