C.M.
Some things that my 3yo son likes: cars/trucks/trains, blocks, puzzles, "workbench" and "tools", Mr. Potato Head and animals. For Christmas we are getting him a Thomas & Friends Mega Blocks set (from Santa), the TAG reading system, and a couple of zhu zhu pets and accessories.
Oh, and there is the active stuff, too - bike, scooter, t-ball set, and football are other favorites.