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.
Harvest - Simple time tracking, fast online invoicing, and powerful reporting software. Simplify employee timesheets and billing. Get started for free.
Hours - Boosting productivity through live, virtual co-working.
Hubstaff - Simple yet powerful employee work tracker with screenshots, timesheets, billing, in-depth reports, and more. Understand productivity issues and act on them.
Futuramo Time Tracker - Futuramo Time Tracker is a time tracking solutions designed for freelancers and teams.
RescueTime - Time management software that shows you how you spend your time & provides tools to help you be more productive.