Applications for smartphones running the Google Android OS have really come into their own this year.

Most of the apps that Google showcased last year in its first Android Developer Challenge were relatively simple location-based services that relied upon Android's Google Maps programme.

However, 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 some of the coolest apps from this year's Android Developer Challenge, whether they're games, reference apps or productivity tools.

SweetDreams

Developer: Inizziativa

Function: Lifestyle

Price: Unknown

One of the more irritating features in modern life comes whenever you nod off to sleep only to be rudely awakened by a late-night phone call.

SweetDreams fixes this by letting you actively manage your phone's behaviour for night-time hours, from disabling sounds for texts and phone calls while directing calls straight to your voice mail.

The best part about the app is that you only need to apply the settings once and then you never have to worry about having your slumber disturbed again.

Created by Spanish developer Inizziativa, this app won't be available on the Android market until next year.

What the Doodle!?

Developer: Che

Function: Game

Price: $1.00 (61p)

Ah, Pictionary. The classic party game that's uniquely humiliating for people who can't draw such seemingly simple objects as fire hydrants or binoculars.

And now people can share their lack of artistic ability with the whole world by using What the Doodle!?, a real-time online game in which users draw pictures of objects on their phones' touchscreens while other users try to guess what they are.

And you thought it was tough drawing puppies with a magic marker on a white board!

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NEXT PAGE: WaveSecure and Plink Art

  1. Must-have downloads for Google Android handsets
  2. WaveSecure and Plink Art
  3. Celeste and A World of Photo
  4. SongDNA and Solo
  5. Speed Forge 3D and Graviturn
  6. Totemo and SpecTrek

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.

WaveSecure

Developer: tenCube

Function: Security and productivity

Price: Free

Now this is the Android app that enterprise users have been longing for!

One of the primary criticisms of Android-based devices is that they lack the strong security protocols of BlackBerry devices and are thus suboptimal for enterprise users.

However, WaveSecure is trying to fix that by giving users the ability to track their phone's location in case it gets stolen, to remotely lock down their phone, to backup all data on their phone and to remotely wipe out all of their phone's data.

If you're an enterprise user trying to convince your IT department to allow your Android phone onto its network, this app will be a major help.

Plink Art

Developer: Plink Search

Function: Reference

Price: Free

This app is perfect for both art lovers and people who pretend they know something about art to impress their dates.
It works like this: if you see a painting you like, you can take a picture of it with your camera phone and send it to Plink Search's online art database.

If the painting is in the database, Plink will send you back information about it, including its artist, the date it was painted and other relevant historical facts about the work.

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NEXT PAGE: Celeste and A World of Photo

  1. Must-have downloads for Google Android handsets
  2. WaveSecure and Plink Art
  3. Celeste and A World of Photo
  4. SongDNA and Solo
  5. Speed Forge 3D and Graviturn
  6. Totemo and SpecTrek

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.

Celeste

Developer: Terminal Eleven LLC

Function: Educational

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

Price: Free

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...

Mobile phone buying advice

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NEXT PAGE: SongDNA and Solo

  1. Must-have downloads for Google Android handsets
  2. WaveSecure and Plink Art
  3. Celeste and A World of Photo
  4. SongDNA and Solo
  5. Speed Forge 3D and Graviturn
  6. Totemo and SpecTrek

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.

SongDNA

Developer: MacroWidget

Function: Reference

Price: Unknown

SongDNA is a sort of encyclopedia for songs, where users enter the title of their favourite songs and get a plethora of information about it, including an artist bio, song lyrics, its chart rankings and even a link to its music video.

This app, which is currently for sale on the Apple iPhone App Store, is not yet available on the Android Market.

Solo

Developer: Coding Caveman

Function: Music

Price: $1.50 (91p)

If you've always wanted to learn to play guitar but have been either too lazy or untalented to do so, then Solo is an app made specifically for you!

Solo cleverly uses the touchscreen to create a series of virtual guitar strings that can be either plucked or strummed to more or less recreate the sensation of playing an actual instrument.

Users can program different chords into the app to get different notes and the app even shows you how to play the chords on an actual guitar should you choose to do so.

Mobile phone buying advice

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NEXT PAGE: Speed Forge 3D and Graviturn

  1. Must-have downloads for Google Android handsets
  2. WaveSecure and Plink Art
  3. Celeste and A World of Photo
  4. SongDNA and Solo
  5. Speed Forge 3D and Graviturn
  6. Totemo and SpecTrek

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.

Speed Forge 3D

Developer: Awesome Software S.A.

Function: Game

Price: $1.99 (£1.21)

You're sick of hearing about racing games on your mobile phone, you say?

Well what if I told you that this particular racing game involves high-powered mining vehicles... that shoot missiles at other vehicles... and that race on Mars!

Interested now? Speed Forge 3D is a visually stunning game for a mobile phone that gives you a good indication of just how much potential smartphones have for mobile gaming.

Graviturn

Developer: Florian Heft

Function: Game

Price: Free

Here's a nifty puzzle-type game that centers on your ability to quickly tilt your screen from one direction to the next.
The game typically starts out with a series of different balls on the screen, colored either red or green.

The balls then begin to roll in whatever direction you tilt the screen. Your goal is to get the red balls off the edge of the screen as soon as possible without knocking the green balls off at the same time.

The premise is simple, but the game gets extremely challenging the more you play it.

Mobile phone buying advice

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NEXT PAGE: Totemo and SpecTrek

  1. Must-have downloads for Google Android handsets
  2. WaveSecure and Plink Art
  3. Celeste and A World of Photo
  4. SongDNA and Solo
  5. Speed Forge 3D and Graviturn
  6. Totemo and SpecTrek

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.

Totemo

Developer: Hexage.net.

Function: Game

Price: $1.50 (91p)

This is a puzzle/logic game in which you have to move different spirits onto a totem pole in groups of twos, threes and fours, except in places where there's a start nearby, in which case you can... OK, so this game doesn't make a lot of sense until you actually play it for yourself. But we've tried out the demo and it's a lot of fun.

SpecTrek

Developer: SpecTrekking.com

Function: Fitness game

Price: $1.99 (£1.21)

SpecTrek is an app that was apparently designed for people who hate the thought of exercising unless they can pretend they're tracking paranormal phenomena while doing it.

The basic idea of SpecTrek is that the world has been invaded by several ghosts and only your mobile phone can detect them.

The device alerts you when there is a 'ghost' in your area and uses GPS to map out where it is relative to your position.
You then must run or walk to where the ghost is and zap it on your phone in order to capture it.

Oh, and because this is an augmented reality game, you get to see a ghost on your phone screen when you approach it.

Mobile phone buying advice

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See also: 15 best Google Android apps for the T-Mobile G1

  1. Must-have downloads for Google Android handsets
  2. WaveSecure and Plink Art
  3. Celeste and A World of Photo
  4. SongDNA and Solo
  5. Speed Forge 3D and Graviturn
  6. Totemo and SpecTrek

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