Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
ClocX - ClocX - freeware analog clock for Windows desktop with many features like calendar, alarms, skins, antialiasing and transparency.
SnapTimer - SnapTimer is a simple, free, portable countdown timer for Windows.
LClock - Longhorn systray clock program
wnr - Better than pomodoro, this timer app balances work and rest.
DS Clock - Keep your time synchronized with Atomic Time servers, using customizable digital desktop clock with westminster chimes.