Thyme - The task timer for OS X.
XNote Stopwatch - Try the most feature-rich stopwatch and timer software on the net for free!
SnapTimer - SnapTimer is a simple, free, portable countdown timer for Windows.
LClock - Longhorn systray clock program
Stopwatch - A Java countdown timer and stopwatch. Features a fullscreen and a resizable window mode.
TimeLeft - TimeLeft is a versatile desktop utility - it can be used as a countdown clock, reminder, clock...