Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
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.
Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.
Hours - Boosting productivity through live, virtual co-working.
EssentialPIM - EssentialPIM is a free Personal Information Manager that keeps up with the times and lets you manage appointments, tasks, notes, contacts, password entries and email messages across multiple devices and cloud applications.
Futuramo Time Tracker - Futuramo Time Tracker is a time tracking solutions designed for freelancers and teams.