K.C.
My son keeps asking for BeyBlades, so he's getting that this year. You can't play it alone, really, since it's a battle type game, but it is great for play dates. If he has friends over on the weekend, I'd definitely recommend it.
If he likes science, consider looking into the various Snap Circuit kits. Amazon has a bunch. I'm hoping my mother in law will buy him one of those. Can't decide between the regular and the glow in the dark.