Time Tracking for Freelancers - A simple, fully integrated time tracker for freelancers
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.
TimeFlip - Human-friendly time tracker
Harvest - Simple time tracking, fast online invoicing, and powerful reporting software. Simplify employee timesheets and billing. Get started for free.
Trackly - Trackly monitors web pages and tells you when they change. Beautifully!
RescueTime - Time management software that shows you how you spend your time & provides tools to help you be more productive.