Google App Engine

Google App Engine is the web development and hosting framework from Google Inc which allows users to upload their web applications and host it for free.
It also allows web developers, to make their application public, allow other users todevelop versions of their applications, create dynamic websites, create websites with backend datastores etc.
Best thing about Google App Engine is that it comes with plenty of free features.
Google App Engine is free as long as :
1) User resource usage quota doesnot exceed 500MB
2) Number of page views is upto 5 million pages per month
Google has a billing system for quotas exceeding free quota.
Users can set their daily budget.