(No word so far about working in Windows 10 or 11 - W2CQ)
WorldClock
A Multi-Timezone Digital Clock
Free Software by Jeff Otterson, N1KDO
WorldClock is a digital clock that can display 1 to N clock faces, each showing the time in a different time zone.
I wrote this program in 1995 when I was working in the Global Network Management Centre of a large telecom, it made the engineers' lives easier. It was originally written for Windows 3.1, so some of the examples shown here have that cartoony look. I have since rebuilt it for Win32, and tested it on XP. I use this on 64-bit Windows 7, it works very well.
The clock faces are attached to the edge of the Windows desktop, and can be placed in either a horizontal row or vertical column from any of the four corners of the desktop.
WorldClock is customized by pointing at the clock you want to modify, and clicking the mouse button two (typically the right mouse button). A popup menu will appear with the following choices: