Moveon.org has been Astroturfing for Michael Moore's Farenheit 911:
In fact, you can reach the Astroturfing page yourself. What's even more amusing: You can use it to send letters to newspapers telling them they've been Astroturfed!
And just in case it disappears, here's the Google cache confirming its existence: http://188.8.131.52/search?q=cache:vYVyXcWc2VYJ:www.moveonpac.org/lte/lte.html%3Fi%3D3004-3347291-3fIxrHkoVHPIERwEN8WIxA%26lte_campaign_id%3D2%26zip%3D06118++%22You+can+counter+their+spin+and+encourage+others+to+see+the+film+by+writing+a+letter-to-the-editor+that+gives+your+perspective+on+the+movie.%22&hl=en&ie=UTF-8.
Props to National Review Online's always great The Corner for point out the story: