Northern California fires - Created by the California Governor's office of Emergency Management, this map has been invaluable for those of us who live near these areas.
Myanmar Cyclone - This KML shows the impact of the original Nargis storm, including the enormous scale of flooding caused by the disaster.
USGS Earthquake Monitoring - This depicts significant earthquake activity in the past seven days. From the placemark balloons, you can also access historical earthquake information.
Google publishes great related information that you can access in the Layers panel, such as the Weather, Gallery > Volcanoes/Nasa and Gallery > Wikipedia. I find these visual depictions to be so much more meaningful that media reports that merely talk about the impact of these disasters. With dynamic mapping tools, you can see exactly where the emergencies occurred and what regions are affected.