I've been using Ocean Waves for perhaps two years now, often turning it on when I'm winding down in the evening or leaving it on a 90 minute timer when I go to sleep. It is possibly the perfect versiontracker application - simple but featureful, unobtrusive, stable, actively maintained, and reasonably priced.

I've registered a number of good applications, but I've gotten hundreds of hours of use out of this one for pennies. Try it.