If your kids aren't interested in a Wii but you'd still like them to get some exercise benefit out of their console, the GAMEROX gaming chair might be the solution. Resembling a couple of mudflaps, the GAMEROX chair moves in all three axis and, by making the child support themselves rather than slump, trains core stability, tones muscle and improves posture.
Video demo of the GAMEROX gaming chair after the cut
Anti-skid feet prevent the whole thing from shooting away across your polished floors, while a removable tripod leg prevents it from toppling backward. The joints have been designed with varying resistance, so you don't slam into the extremes of flexibility.
Currently it's designed for kids aged between seven and twelve, as long as they weigh under 175lbs. No word on price, but it should be available in the "near future". We'd like to see an adult version, please!