Clocks - A minimal world clock app for your Mac's menubar
ClocX - ClocX - freeware analog clock for Windows desktop with many features like calendar, alarms, skins, antialiasing and transparency.
Spacetime - Work hour and time zone management for distributed teams.
LClock - Longhorn systray clock program
Every Time Zone - Online tool for keeping up with times around the world.
DS Clock - Keep your time synchronized with Atomic Time servers, using customizable digital desktop clock with westminster chimes.