We were short a player, so instead of playing D&D yesterday, we played a bunch of different games with my father-in-law.
Magic: the Gathering. My nine-year-old son is getting better and better at this one. He's getting pretty good at finding synergies between cards and using them in-game, though I'd like to see him be more aggressive. He tends to build up a lot of creatures before launching any attacks. So far it's worked, but I'll have an answer for it soon.
Munchkin. My gnome bard won it what turned out to be a nailbiter. I only won by calling in my doppleganger reinforcement.
Poo, which is a very silly game about monkeys flinging their poo at each other. I got covered in poo very quickly and was out first.
Ascension: Chronicle of the Godslayer is a deck-building game. The primary goal of the game is to collect the most "Honor", which is earned by defeating monsters and collecting certain cards.
Quarriors is similar to deck-building games, but your "deck" is comprised of different dice that you then have to roll.
Thunderstone is yet another deck-building game, with a very D&D type of theme to it. You can either buy stuff in town, weapons, characters, items, spells, or you can go fight one of three monsters waiting in the local dungeon.
These deck-building games are pretty interesting. I wasn't too keen on them at first, but they've definitely grown on me the more I've played them. My oldest son has grokked them pretty well and tends to win. They don't require the massive time investment of Magic: the Gathering and deliver a fun competitive experience. I probably won't pick any up, as my father-in-law has an extensive library and we typically only play them when we go over there. We have been playing a lot of Magic at home, though, and I'm very much enjoying getting back into that whole thing.