This is something I found when looking through iGoogle apps. I've missed my piano since I've been out here in California, even though my musical skill leave much to be desired.
This is far from perfect. The obvious drawback is having to use keyboard keys (or the mouse) to strike the notes. This is very awkward for anyone who knows where the finger positions are! Also, it isn't tuned correctly; it's a whole step off. But, I'm just glad to have something to make music with, even as difficult as it may be.
I found
a site where you can print FREE staff paper, and have tried to notate as least one song using this weird keyboard method. Slow going, but I'm only doing this for myself, when I'm alone, so time doesn't matter.
It really is better than nothing, and sounds better than the "midi" sound that you'd expect from a cheap keyboard.