Download C# source and ClickOnce installer Needs .NET Framework 2.0

Double-click to open the fancy world clock/map:


The yellow line is noon, blue is midnight. The bright/dark areas are split at 6:00 AM and 6:00 PM. It's not 100% accurate given the peculiarities of time zones (and of course the sunset/sunrise times are rough guesses at best, especially near the poles) but if one of the lines is over England, then that's the GMT/UTC time. (Although, again, not necessarily the local time due to daylight savings)

I was planning on putting in a list with local time for cities around the world, but it turns out to be rather annoying. You can get the local time zone information, and Windows does have a list of time zones somewhere (check the Date and Time control panel), but you can't easily get at that list. (And, of course, you would still need a list of cities with lat/lon and time zone)