xSkyDesk for Mac

From Brad Anderson:

The simulation accurately portrays the sky during the day and the stars at night. The main goal is the synchronicity between what you see outside on a clear day and the simulation. In this way, the Great Outdoors can be brought inside and seen through your computer. While experiencing the outdoors is preferable, most computer workers do not have the opportunity to even marginally experience the sky overhead. xSkyDesk is the way to be connected to your environment.