I found these at my library a few weeks ago and my kids are really enjoying them!
We have the Boxcar Children one, and the Chronicals of Narnia one.
It fits nicely into a pocket or have it hang from their necks. They remind me of an IPOD -really small and portable. The only catch is that we have to provide the headphones and we only have one pair! It sounds easy enough to just go out to buy another pair or 2 more....but my memory fails me. Oh well!