How fun! And what a nice thing to do!

I have a five-year old nephew and he loves super-heroes, like Spiderman, Batman, etc. I always try to get him something somewhat educational too, but that's fun. He just started kindergarten and he loves numbers, so this year one of his gifts will be a puzzle-book that uses numbers. Like, connect the dots and mazes and so on.

I would also recommend legos. They are fun for almost any age, for girls or boys.

Oh, I also wanted to suggest art supplies, like crayons and construction paper, play-doh, etc.

Whatever you decide on getting I'm sure it will be greatly appreciated by him.