We periodically turn off our TV, hide the remote, ban the computer etc. - usually when behaviour (the kids', not ours) has hit an all-time low. Once we even put the TV in the garage for a week just to avoid the temptation of giving in! If you too are looking to lose some screen time, April 19th - 25th is the official "TV turn-off week" (also referred to as digital detox).
The first such event was put on in 1994 by Adbusters Magazine and a few other collaborators. The Centre for Screen Time Awareness (CSTA), based in Washington, is the current promoter. This isn't an event that's getting a lot of screen (or print) time though. Even the CSTA has almost nothing on its website. The best resource that I could find is published by the Media Awareness Network, a non-profit organization based in Ottawa that helps people understand how the media works and how the media may affect lifestyle choices http://www.media-awareness.ca/english/resources/educational/teachable_moments/tv_turnoff_week.cfm. It's got some quick statistics, some topics to discuss with your kids and links to other resources as well. The event is also publicized in the April 2010 Scholar's Choice Toy Talk Newsletter and has in the past (though not this year) been promoted by the OCDSB.