Mavenlink - Resource planning, time tracking, project financials, collaborative project management, and performance analytics all wrapped up in one intuitive solution.

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.

BigTime.net - BigTime is a leading Professional Services Automation software that helps you scale your firm by giving you the ability to track & act on your operational metrics. Even with remote work, easily manage time, expenses, & billing for multiple projects.

Harvest - Simple time tracking, fast online invoicing, and powerful reporting software. Simplify employee timesheets and billing. Get started for free.

Kimble PSA - Kimble PSA provides professional service organizations with real-time diagnostics of their customer engagements.

Hubstaff - Simple yet powerful employee work tracker with screenshots, timesheets, billing, in-depth reports, and more. Understand productivity issues and act on them.