Ask HN: We realised one of our pet projects. How to market this?

We have been working on a small iphone app on the side, and we have just released it. We have done this project entirely for fun and gaining exposure to the app store(frankly, it wasn't that bad - compared to the horror stories we've heard). We released two of versions of the app, free and pro. We are not expecting any profit from this, but it would be nice to have some users and get some feedback. Do you have any pointers for marketing this?

URL : http://www.grammarfungame.com/