Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
Be Focused by XWaveSoft - Simple Pomodoro timer in your Mac's menu bar
Alarm Clock Tab - Web based time tools including alarms, timers, stopwatch, and time zone converter. Resources also include Tabata, Pomodoro and other useful tips and tactics for managing time and time tracking.
Flow - Stop managing projects from your inbox.
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.
Doropomo - Inverted Pomodoro focused for a truly work/life balance