aladygma is a projekt started february 2008, i am following it, it grows great all over the world, tehy have hidden buttons on the page
iknowwhatyouwilldoonthischristmas is a smaller nice viral campaign started with 2 videos
http://de.youtube.com/watch?v=tLfv9zEOk60
http://de.youtube.com/watch?v=yAMPy52kV4k