We got DS5 the snapcircuits upgrade kit. I HIGHLY recommend snapcircuits for kids that are into science and building things, DS love them. Also, are getting him a contraption game through Mindware, qwirkle, gobblet, perquacky, a family pastime game (our first one we are going to try) a few more thinkfun games and puzzles (he loves games) and a physics workshop thing. And some science toys and graph paper for his stocking. For my DD2.5 we are getting her some puzzles, a dollhouse, and lots of girly stuff and dressup things which is her current interest.
