For the global visualization of time zones and clocks on your desktop (freeware):
Desktop Sun Tracker
This software displays two versions of the world map, a day, and a night version,
and fades between them to show which portions of the world are in daylight,
and which aren't. In other words, this is a dynamic wallpaper that
updates based on where the sun is relative to the surface of the earth.
Breitling World Time