Google Crisis Map for Hurricane Sandy: features layers to display evacuation zones, open shelters, weather information and live webcams. The map also includes a storm surge layer that shows the probability of a storm surge over six feet in the city.
XKCD's map of online communities (2007) (Note the size of size of MySpace in this 2007 version as compared to the size of Facebook in the 2010 version at http://xkcd.com/802/ )