If you have a budget for marketing campaign, you can try paid options like
Some examples of the websites are:
Try to find those
Free App A Day sites and make your application free for a while. This will generate a little buzz, and get you some (hopefully good) reviews on your app.
One strategy can be to create a mobile version of you web site. There are some articles on Seomoz about mobile SEO. Another one is to use niche web sites for mobile applications to promote them. You strategy for get noticed shouldn't be different from strategy to get noticed with conventional application. It is just another medium. In addition to web advertising you can use other medias to promote you application (TV tech talk shows, magazines).
It may be worth to spend some of you time to research ways to promote on facebook.
There are more than 150 million active users currently accessing Facebook through their mobile devices.