I just let my kid play various games on noggin.com (and nickjr.com, since he navigates there from noggin.com). He's getting pretty good at some of the platformers.
he really likes playing drums, but he sucks at rockband.
I borrowed a Wii for a month (too damn expensive to but outright, I'm no balla) and all I really played was Wii Sports. It was simplistic but still addictive as hell. Especially the tennis. Loved tennis.
FWIW - 2105 was my tennis rating, and I got up near 1600 at golf (usually shot -6 or so for nine holes). Never played baseball or boxing, sucked at bowling.