What I haven't been able to put down recently is this Fruit Ninja.
I play the Puss in Boots version but I'm sure the normal version is just as good.
All you basically have to do is slice the fruit and avoid the bombs and it is insanely addictive. You have three lives and you lose one everytime you miss a fruit, slice the magic beans and you get an extra life.
My best score is almost 500, but it takes some people longer to pick up these things ;)