Sometimes you really do need to get away. Escape, part search engine and part research project from students at the MIT Senseable City Laboratory in Singapore, shows you the cheapest flights out of any given city. Just put in a location, and you get color-coded connections to everywhere around the world.
There are actually two data visualization views: 1) The temperature view: plotting the destination nodes based on temperature range (X axis) and temperature difference (Y axis). 2) The map view: plotting the nodes on a geometric map based on coordinates with force layout.