http://uploaded.to/file/5p0svj
It's a small uncomplete piano, nothing compared to if you actually have a keyboard, but it's actually quite fun to hammer on your computer keys to play some music :P It's controlled by the middle and top row of keys, like this:
we tyu op ¨
asdfghjkl;'\ (those last three of the bottom row and the last one of the top row are appearently like that on an English keyboard, so if it does not work for you, just turn your keyboard settings to English. I think it has to be Great Britain English, I do not know about American)
It's written in Java, we used it in class when we were dealing with Greenfoot way back.
A small egyptian riff that I used to play on the guitar works here as well:
sdfds-sdfydfs sdfds-sdfudfs sdfds-sdfydfdfdfdydfdfdudfs (these are not the musical notes, these are the computer keyboard keys)
Just jam like that, it's quite fun actually :P