One thing that will encourage potential users of your application is good reviews. However, users are not that inclined to give good reviews to programs, even when they got them for free and have used them many times.
Lee Stott did a great little blog post a while back that shows how to add a review facility to your application. It is very sensibly designed, in that it only nags once, after ten uses of the program, so it doesn’t become a pain for the user.
You could also use the same technique to add timed release behaviours to your application, so that it could suggest new things to do over time.