I moderate their gaming habits by hogging the PS3 myself 
But seriously: Console lives in the lounge, so no hiding away in bedrooms and playing out of sight. Play regularly but not for too long at a time. Play is conditional on doing other things first - chores, reading, homework. Other hobbies, interests and sports: one son does diving, the other basketball and skateboarding, we all go to the gym together (well not the Mrs) twice a week. Let them have the occasional gaming marathon.
Oh yeah, and because I'm a gamer it's something we can have fun with together. Not like boring parents who don't like gaming at all...but will happily sit and watch TV most of a night.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix
