The GExplorer interface makes use of both cursor keys and mouse. Use of the interface is very straight forward but keen users can make very complex camera movements through various key combinations. Essentially the GExplorer interface in "Places" allows you to move around as if you have one of those 3D Navigator input devices. You wonder why Google Earth doesn't offer this out of the box.
The website can be found here http://www.planetinaction.com/ and a video of "Places" in action can be found: