In the past couple of weeks we've become addicted to Rock Band II. We were already addicted to Guitar Hero, but with the drums and vocals included it's just that much more fun, especially in a group (which we've had a lot of lately)! I can count atleast 6 people who have been hesitant to try it, and then stay up until 3 AM playing it (ahem, ahem... you know who you are :)
Good thing we didn't get a Wii like we were thinking about (YET), or we would probably never go to sleep. If you don't have one or the other, you should really get one. It entertains people anywhere from 9 months old to 50+!!