Play the Piano
Play on the YouTube piano.
An interactive video from Kokokaka.com
UPDATE:
The piano above is from Kokokaka.com.
And the piano below is from Instrumentube. They have an interesting channel on Youtube. Checking on Youtube you will see that the piano from Instrumentube was posted before the piano from kokokaka. Anyway, both of them did a great job with a brilliant idea.
Thanks for the tip, Guy.