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.

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.

Asana - Asana project management is an effort to re-imagine how we work together, through modern productivity software. Fast and versatile, Asana helps individuals and groups get more done.

Hours - Boosting productivity through live, virtual co-working.

Basecamp - A simple and elegant project management system.

Futuramo Time Tracker - Futuramo Time Tracker is a time tracking solutions designed for freelancers and teams.