I recently read a very good interview with Jason Fried on The Great Discontent, and one of the answers towards the end of the interview struck me:
The other advice is to focus on one thing. I see a lot of entrepreneurs build something and then move onto the next thing and the next thing and the next. Building something is only step one. It’s not that hard to put something out there. Building on top of that to maintain and improve it is actually the harder thing to do. Anyone can release something, but it’s much harder to polish and refine it over time once it’s out there.
I admit I've been tempted by this same thing many times—trying out new idea after new idea, leaving the old to gather cobwebs in a closet. Lately I've been refocusing on some of my older, mildly successful projects, like my Hosted Apache Solr service and Server Check.in (they're not that old compared to other mature services, but they're old for me).