What Android apps/features can't you live without?

This thread was in the Apple forums, and I am real curious to see what the Android users post, as it would be interesting to compare what is considered important to each OS user base.

Here is the Apple post for all you dual platform users: http://www.theverge.com/2012/10/22/3541522/what-ios-apps-features-cant-you-live-without.