I wish to control my step-son's computer usage with some kind of scheduler. I wish to restrict access to WoW and other installed games, and Internet certain hours the day, while it being non-intrusive when 'unlocked'.
Some better quality routers can open ports at sheduled times. In addition to this, lock the pc with a static IP and take away his account's network config permissions (will stop him physically bypassing the router).
Or get a software based firewall with the same feature and lock it with an admin passwd (not as foolproof though).
Lol, when i wasa kid, a simple but very loud "Get off that computer NOW!" rant usually did the trick if i was in front of it "too long", otherwise it was confiscated :(