Earthquake Information from the USGS
USGS provides detailed information concerning earthquakes. What I liked the most were Google Earth kmz Files:
M1+ Real-time Earthquakes, Past 7 Days
They display real-time information, updated every 5 minutes for California Events and 30 minutes for world-wide events. There are 2 kmz files available:
* Earthquakes colored by age
* Earthquakes colored by depth

You can choose what magnitude events you want to see, you can choose one particular event and see details or go from one event to other kmz maps such as: Historic earthquakes since 1970 (M 3+):

There is also a Shakemap available:
