If you have clients, vendors or colleagues in multiple timezones around the world, like me, you may find the World Clock Deluxe utility to be invaluable. I formerly used JetClock, a replacement for the standard Mac OS X menu clock, but the memory leak in the latest version made it too troublesome to continue using. Instead, I upgraded to the excellent World Clock which lets me quickly check the time extremely conveniently:

I’ve found that sticking the Clock to my “Desktop” is extremely convenient, much more than using a Dashboard widget – which can often take several seconds to load. Instead, setting the “Level” of the World Clock to Desktop, hitting the expose command to show my desktop also conveniently lets me review the current time in all relevant areas.