The latest version of Google Earth contains a hidden feature: a full-fledged flight simulator! Press Command+Option+A in OS X or Ctrl+Alt+A on a PC or Linux box and you’ll be greeted with a hidden dialog box that lets you choose an aircraft (F16 or SR22) and an airport. Once you’ve made you selection, you’ll be placed inside the aircraft. You can then fly around the globe in a free flight simulator, viewing the scenery that is pulled from Google Earth’s map files.
I wasn’t able to get things to work at first, so if the key combo doesn’t work for you, try zooming way into Earth and try again. It seems like you can’t activate the feature when you are out in space looking down on the eath. Once you’ve activated the feature, it will be available from the Tools menu.
Force feedback joysticks are supposed to be supported, though I’ve only been able to test with a mouse and keyboard. The basic controls are PageUp/Dn for thrust, G for gear up/down, Left/Right for aileron, Up/Dn for elevator and Shift+Left/Shift+Right for rudder. You can also click the screen to enable the mouse to control the aileron and elevator controls. See the link at the bottom for the full set of controls.