I used to read to my nephews when they lived with me. They loved it. I used to read to them whatever book I was reading at the time. During that time it was mostly William Shatners Star Trek books, and Clive Cussler novals.
I tried to teach them games, but being twins, they were more interested in competing with each other for lap space in front of the PC monitor. So Reading was far more effective at keeping them occupied until they fell asleep.
It is funny how much reading helps a kid to develop learning skills and a life long desire to read.
Puzzles, legos, and erector sets also work well.
My nephews love their legos, and have build some amazing things lately. They are finally beginning to understand the joy of creation that comes from making things out of nothing. I have introduced them to DOGA, and now whenever they come over to visit, (IE there dads needs something from me) they want to make stuff. I am using two of their fighter designs in the new Gamilon set that I am working on now. (Starblazer set)
I hope to one day know 3dmax or other and be able to teach at least one of them how to use it. I am already teaching them both photography and such, and will more than likely buy them each a nice 35mm cheapy camara this christmas.
There dad teaches them mechanical stuff such as bike work and wood working, there mom also reads to them and tries to be firm and proper, and the rest of us, when we get to see them, just enjoy including them in whatever we are doing. But being twins, they are a handful together, apart they are very differant. But when they get together, they become something else, an entirely new personality emerges, I call it the Terror Bot.
I miss being a father, I really never got the chance... RL is funny that way.
Be sure to let us know which scifi show the new kid on the block likes most.
And when you loose your first game of hot seat to the child you must let us know