Once upon a time when my little boy was only 2 years old, I noticed he liked to imitate what I was doing on my computer. So I gave him one.
I chose the ALIX 1 because it uses very little power, can run from a CF card and has a ready-made desktop environment available in iMedia Linux.
With very little effort, I built a fully-featured internet-capable box that was much less likely to get him into trouble online than one with Windows.