Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Google Calendar - Spend less time managing your day & more time enjoying it
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.
24me - Next Generation Personal Assistant
Remember The Milk - Remember The Milk is a task and time management application for mobile devices.
Business Calendar - Powerful and easy to use calendar app for Android including weather, widgets and tasks.