This year's Android Developer Challenge showed off an enormous variety of complex applications that let users play guitar, learn about astronomy, get information on famous art or even chase down ghosts. We've picked out the 12 coolest apps.
Developer: Terminal Eleven LLC
Price: $1.99 (£1.21)
Astronomy buffs should love this augmented reality app, which uses GPS locations to determine the current locations of the sun, moon and the major planets, even if they're currently obscured from your view.
You can get the estimated times for when the moon and sun will rise and set, as well as the trajectories that planets will take across the sky.
And because the app is augmented reality, you'll get to see pictures of Saturn and Jupiter on your phone.
A World of Photo
Developer: Michael Elsdörfer
Function: Social networking
This is an interesting social networking game that lets you 'spin' your phone until it picks out a random fellow user from somewhere around the globe.
Once that user has been chosen, you can request that they either send you a picture of themselves or of their immediate surroundings.
The point of the game, if there is one, seems to be to make contact with as many different people in as many diverse locations in the world.
Now if only someone could sign up Kevin Bacon to play...
See all mobile phone reviews
NEXT PAGE: SongDNA and Solo