Format shifting fun for the whole family

I've recently jumped ship, from the Playstation 2 to the xbox, mostly for the insane hackability of the xbox (the xbox is basically wide open now and can be used in all sorts of ways, most notably as a media server).

Now that I'm using the xbox for more than a few minutes per week, I'm wondering what games I should have aside from the usual obvious suspects for first person shooters and sports games.

What are some good simple fun group games that even non-gamers can use? So far I've only found a Trival Pursuit game that's so-so. If you know of any good 2-4 player games that anyone can enjoy, I'd really appreciate if you dropped me a line.