In my experience, developers suck really bad at promoting the stuff that they make. We seem to have a "if I build it they will come" mentality most of the time, which isn't a great way to achieve any sort of real success with a software product. Marketing is a vital step in the process, and is worth your thought and effort.
This talk by Tim Oliver is really good, and he gives many concrete examples of how to properly market an app. Definitely check this one out.