It is indeed "too useful" for my kids, too :-) The two year old came into the parent's sleeping room this morning, just to climb over me (still in Bed), grab the N810 and shout "SAM!" - she appreciates it very much that I keep 36 episodes of "Fireman Sam" on my tablet...

The 4 year old likes TuxPaint and to type around with the keyboard (learning the ABC).
I also started to put some Flash-based music "apps/games" on the N810 (inspired by PyAno, but the Flash stuff is much easier on the device).