Is your child not quite ready for proper typing, but does she love "typing stories" on the keyboard The trick is finding a program that allows them to muck around without the possibility of triggering special functions through some keypress or mouse movement. With the help from Greg Black & James McPherson on the #humbug channel, this is what I have devised for Phoebe's Eee PC:

Using emEditor, create a menu item "KeyBashing" somewhere and give it a keyboard as icon. Commandline /usr/bin/uxterm -fn 10x20 -geometry 79x21+0+0 -title 'Keyboard Bashing!' /home/user/typer.sh

typer.sh contains the following:

stty -isig
echo Welcome! Start typing - exit by closing window
echo
cat >/dev/null

Make typer.sh executable with chmod +x typer.sh
The stty -isig command disables keycombos like Ctrl-Z and Ctrl-C.

After editing menus, you can use Ctrl-Alt-Backspace to restart X.