Thyme - The task timer for OS X.
XNote Stopwatch - Try the most feature-rich stopwatch and timer software on the net for free!
Stopwatch - A Java countdown timer and stopwatch. Features a fullscreen and a resizable window mode.
SnapTimer - SnapTimer is a simple, free, portable countdown timer for Windows.
Timer and Stopwatch - Online Stopwatch, with start alerts, lap times and sounds. Save details of your timings in a text file.
LClock - Longhorn systray clock program