you know what babies love? audio visualizations (like the ones for windows media player, winamp, or sonique). has the same effect as giving a grown adult acid (only without the brain damage). what you could do, it create a fullscreen window that displays a visualization (i would suggest windows media player visualization support because they resize nice, it's a format guaranteed to be around for awhile, and it should be easy to tie into). then when a baby hits a key, a sound plays which makes the screen dance. depending on how you hook into the wmp visualization, it would even be posssible to send simulated bass thump to the visualization even when a sound was not attached to that key. just an idea. i would probably use it too. and best of all, you could set it as your screensaver. that way, if you leave your computer for an extended period of time, it will automatically engage and your computer would be baby safe (or secure from coworkers). pretty clipart could always be displayed in front of the visualization. anyway, babies would love it and it would broaden the audience a bit. it would be a really cool project. you could call it "baby crack" or a tamer "baby keys".
-cracksloth