Check this out!

As babies smash on the keyboard, colored shapes, letters and numbers appear on the screen. Baby Smash will lock out the Windows Key, as well as Ctrl-Esc and Alt-Tab so your baby can’t get out of the application. Pressing ALT-F4 will exit the application and Shift-Ctrl-Alt-O brings up the options dialog.

I wrote BabySmash! for my 2 year old and 5 month old so they could bang on the keyboards of my Windows machines without hurting anything.

Baby Smash! by Scott Hanselman.