AlfaMini

Shows current time and date of other time zones, next to your computer clock. Can display 1 to 9 clocks at same time.

Replacement of Windows tray clock, support Winamp skins

Global Time Synchronizer is a versatile time keeping tool that has many features including the ability to modify the look of your standard desktop clock, an easy-to-use, convenient interface that uses skins to modify its appearance and much more.

Skinny clock is a freeware utility allowing you to display current time on your desktop. You can customize taskbar clock as well.

WinBoss is a system tray application that hide (all) running programs with one keyboard hit. Useful when Boss is coming, or to hide less important application from cluttering the desktop.