The Google Crisis Response Team has released a number of Google Maps in response to the recent events in Japan. The Traffic Performance Map uses data provided by Honda to show which roads have been recently usable.
The Shelter Map uses data provided by the newspaper Mainichi to show the locations of shelters. It is possible to click on each of the marked shelters and get details on the number of displaced persons currently being sheltered.
The Rolling Blackouts Map shows areas that are affected by power outages. It is possible to search the map for planned power outage information by address or post code.
This map from Kuippa (not from Google) shows the areas affected by the current problems at the Fukushima Daiichi Nuclear Power Station. The map shows the different exclusion zones imposed around the plant.