Be Focused by XWaveSoft - Simple Pomodoro timer in your Mac's menu bar
Toggl - Toggl is an online time tracking tool. It features 1-click time tracking and helps you see where your time goes. Free and paid versions are available.
Doropomo - Inverted Pomodoro focused for a truly work/life balance
Harvest - Simple time tracking, fast online invoicing, and powerful reporting software. Simplify employee timesheets and billing. Get started for free.
Flow - Stop managing projects from your inbox.
RescueTime - Time management software that shows you how you spend your time & provides tools to help you be more productive.