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.
Worksnaps - Worksnaps is a unique service specifically designed to track time for remote workers, telecommuters and freelancers.
Clockify - Simple and free time tracker. Perfect for small and mid-sized businesses as well as freelancers. Unlimited projects and users, unlimited productivity. Get all the premium functionalities, completely free.
Harvest - Simple time tracking, fast online invoicing, and powerful reporting software. Simplify employee timesheets and billing. Get started for free.
ManicTime - Track your computer usage and use collected data to accurately tag time.
Visual TimeAnalyzer - TimeAnalyzer is a extensive reporting time tracking, timesheet and project tracking software. Automatically monitoring all PC activities. Track working time, projects, costs and internet use.