As many of friends, I recently acquired a HP Touchpad largely due to its low price. I don't really need a tablet, as I am sitting in front of computes almost all the time. My original plan was to turn it into an interactive cat toy, at least sometimes, so I can keep the two cats entertained while I am working.
Unfortunately, I could only find one game designed for the cats "The Catnip Collection". According to its website, it "is a variety of toys that will amuse and challenge your cat and its human".
The reviews seem pretty decent (4 out 5).
Even though it is not free anymore, I bited the bullet and bought the app. Unfortunately, the cats are not even remotely interested! I think that the problem is the objects (insects, balls, etc) are constantly moving instead of stopping and moving randomly. So the cats get bored after 5 seconds.
Hopefully the app developer will see my post and consider improve the game further. For the smart cats who play with human all the time, we need something that is really challenging!