T-Clock Redux - T-Clock Redux in an enhanced fork of Stoic Joker's T-Clock 2010 with ISO week number support...
Timer Tab - Online countdown timer, alarm clock, and stopwatch.
ClocX - ClocX - freeware analog clock for Windows desktop with many features like calendar, alarms, skins, antialiasing and transparency.
Gestimer - For those little reminders during the day
DS Clock - Keep your time synchronized with Atomic Time servers, using customizable digital desktop clock with westminster chimes.
Online Stopwatch - Online Stopwatch is free to use online tool that allows you to keep track of the important events and tasks that you are performing.