Today, Google released a new version of its popular world browsing software, Google Earth. Some new features that was included in this update is being able to look at historical images, explore the ocean, and record your own tours. You also are able to explore Mars through Google Earth in addition to seeing the Earth and Sky. The ocean layer allows you to see the bottom of the ocean and 3-D models of shipwrecks. The recording feature is quite simple and you can add narration to it too. The new version is available at the Official Google Earth Page.
Tour of Google Earth 5.0
Demo of Google Ocean (I know this one looks similar to the video above, but it is a different one)
More Info:
Google Earth Blog (Unofficial)