Office Timesheets - Professional Services Automation
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
HarmonyPSA - HarmonyPSA - Professional Services Automation (PSA) for IT Businesses
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Timewatch - Timewatch offers time tracking, expense management, resource scheduling and professional services automation solutions.
Remember The Milk - Remember The Milk is a task and time management application for mobile devices.