Goldfish Music Box Lite is currently free

This app has just gone free, but I don't know for how long. If you don't know about it, here's the description:

This application converts color into music. It can turn your goldfishes or any moving objects into an interactive music box.

You can also use it as a musical instrument to create tunes with the environment. Listening to shimmering lights and wandering clouds may become your next adventure.

Open up the application, pick colors to represent different music notes and listen to the colorful world.

Please visit: http://db-db-db.com/goldfish/ for more info and demo videos.

Note: LITE version supports only one type of sounds.