For a project that really showcases what can be done with an Arduino, processing and a lot of imagination comes the "Visual:Drumset" by 17 year old Dominik Koller. By mounting vibration sensors on the bottom of each drum in a kit, measuing the values with an Arduino and sending them back to a PC - processing can then control projectors which will display visuals on the actual drums. It's a magnificent visual effect generator which won Dominik won an award.
An interesting project and quite motivational. For more information visit the project website (opens in Google Translate). And for more, we're on twitter and Google+, so follow us for news and product updates as well.