Best Android Applications

I'm new to Android and I am looking for the best apps you use everyday, please post your findings.

I am also looking for "intelligent" games for youngsters.

Doublemill 2 Nine men's Morris by +1 Labs, and Checkers Free, by AI Factory Limited. Both quick time killers.

Simon Tatham's Puzzles for Android (free and open-source)

Solitaire Chess free from Thinkfun

Enjoy Sudoku by Jason Linhart. The graphics look very amateurish, but feature-wise, it's the best Sudoku app IMO. It's one of few apps that I happily paid for both the Android and iOS version.

flappy bird, candy crush

Google Sky Map