Does anyone know of a program that will DISABLE my internet connection / wifi for set periods of time?

I'd really love to have a timer program like Minuteur that will let me ruthlessly ban myself from email, RSS, and procrastinatory online fact-checking when I need to focus on the task at hand.

I know, I know, I can just unplug my router and chuck it up onto the roof until I'm done working, but I'm looking for something more elegant. (Besides, I have a neighbour with wide-open wifi.)

Many thanks,
Mike McPh