AnyTime for Mac

Install a number of different clocks into your taskbar

AnyTime is a tool that allows you to add different clocks into your taskbar. The clocks are based on countries and country times, which is why each comes with its own flag. Sadly, it doesn't allow you to add cities, which means you have to figure out time zones in order to get the right time on each clock. You will need to set the time yourself, but that is no problem since you can get the time for each timezone quite easily off the Internet.