Do you know OSU?
Well, OSU is a very fun game for pc. You have to press special Hit Objects in the right moment while listening to music.
After playing it a bit I thought to myself: ,,Would it be possible to play this game in a browser?”
So I wrote a little, by far not complete, OSU clone in HTML5. It is very basic but it shows how you can build funny games without big effort in HTML5.
Try it here: http://alexander-luecking.de/canvas/audio.html (Works best in Google Chrome)
I used the processing.js library by John Resig to draw on the <canvas> element, <video> for the background video and <audio> to play the song and measure the current time.
Google Chrome had some problems with mp3 files but ogg worked perfectly.