Google's Cloud Developer Challenge 2013 was launched at the beginning of September. The app submission period for the contest is October 22nd - November 21st so there is still plenty of time to enter.

To quote from the contest's  FAQs:

The Google Cloud Developer Challenge is a contest designed to motivate and reward entrants who develop applications that are based on Google’s Cloud Platform that are original and relevant to the region in which they live.

Submissions have to use App Engine and have an appspot.com domain.

There are six competition regions: 

• Sub Saharan Africa
• Middle East and North Africa
• India
• South East Asia
• Latin America
• United Staes. Europe and rest of world 

and two entry categories: 

• Enterprise / Small Business Solutions, Education, Not for Profit
• Social / Personal Productivity / Games / Fun

The competition is the successor to last year's Google Apps Developer Challenge and if you are looking for inspiration, or clarification of what the judges will be looking for, details of its winning entries may help.

Teams for this contest are limited to three people, who must have reached the age of majority in their country of residence and there are the usual exclusions -  Quebec, Cuba, Iran, Syria, North Korea, and Sudan.

The contest has two rounds. From the first round up to 10 apps from each of the categories in each region will be chosen to go forward to the semi-finals in each region. All teams  that make it to the semi-finals will be awarded Android devices.  Any university team made up entirely of student or staff of a university that makes it to the semi-finals will get $1,000. Also, in order to encourage participation from women, $2000  will be awarded to all-women teams (including individuals).

After semi-finalists are announced (December 5) there will be a month in which they can polish their apps, to add features, improve stability, performance, etc before the final submission (January 5th).

There will be 12 first prize winners, one for each of two categories in six regions, each receiving $20,000 with a further $18,000  going to any university department that enters a prize winning team.

In addition up to 6 mentors (one from each region) will win an all expense paid trip to a major developer conference anywhere in the world to the tune of $5,000.

Apart from the compulsory use of Google App Engine and having an appspot.com domain, the criteria for the contest are: 

• Originality of Concept
• Relevance to Region
• Polish and Appeal
• Usability on multiple screen sizes
• Accessibility
• Indispensability: Is the application compelling and/or essential?
• Amount of user interactions on their app (comments, +1s, FB Likes etc)
• Google+ Sign-In / Integration (Not compulsory:Bonus Points)
• Creative use of Youtube and Google Maps APIs (Not compulsory:Bonus Points)
• Use of other Google platforms/APIs (Not compulsory:Bonus Points)

Among the resources listed on the contest website there's one that is worth knowing about by any developer wanting to use Google App Engine or Google Compute Engine - the Google Cloud Platform Starter Pack, which offers $1,000 of credit for Google App Engine and $1,000 of credit for Google Compute Engine for selected applicants who can provide a promo code and details of what their organisations plans to build.