Clock Tray Skins is the advanced replacement for standard Windows tray clock.
Clock Tray Skins Lite v2.1 - Freeware!
Windows clock utility for Windows NT/2000/XP/2003
Clock Tray Skins is the advanced replacement for standard Windows tray clock. See the time, day, and date in different skins. Over 50 skins are included in the distribution.
It's also an atomic-time synchronizer.
And it is absolutely free!
http://www.drive-software.com/windowsclock.html