Google Calendar - Spend less time managing your day & more time enjoying it

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.

Simple Calendar - A simple calendar with events (optional recurring and reminders), week numbers and a customizable...

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.

Business Calendar - Powerful and easy to use calendar app for Android including weather, widgets and tasks.

Basecamp - A simple and elegant project management system.