I just purchased our "Santa" gift. It's kind of a "BIG" one--which isn't fun-but it's one that I'm hoping will have multiple pluses in our family. We are getting the kids a Wii!
It comes with several sporting games and even a second joystick for more than one player. This is good, as I have four kids.
The nice thing about the Wii--you actually have to play it. You can't just use your fingers. If you are boxing--you literally have to hold the joystick and box. Bowling and tennis are the same way--I think the kids will enjoy it--and it will get them up off of the couch a little more often!