Trello

A great organization tool that takes your TODO lists to a new level. Lately they added a feature to add items (cards, they call them) from email. You might also like Wunderlist 2.

Trello @ Google Play
Trello @ the web

Evernote

Great note manager that stores your notes online. It also has a desktop (Mac/Windows) app and a brower app. It's not perfect because you can't edit notes with complex formatting from your phone, but it usually works very well.

Evernote @ Google Play

Wunderlist 2

Nice TO-DO list manager app/widget that also lets you access your lists from a browser and stores your data online so you don't lose your TO-DO's when changing your phone. Check out Trello too.

Wunderlist 2 @ Google Play
Wunderlist 2 @ the web

Business Calendar

This is my favourite calendar. I especially like its widget and how easy it is to add/edit events and see my different Google calendars (work, personal, etc) in custom colors.

Business Calendar @ Google Play
Check out the paid version for more features.