Google App Engine is a developer tool that enables you to run your web applications on Google’s infrastructure. The goal is to make it easy to get started with a new web application, and then make it easy to scale when that app reaches the point where it’s receiving significant traffic and has millions of users.

Google App Engine enables you to build web applications on the same scalable systems that power Google applications. It also provides an API for authenticating your users. If you choose to use this, anyone with a valid Google Account may sign in your application. It saves you some time on building users registration and managing users accounts. At the moment, every Google App Engine application can use up to 500MB of persistent storage and enough bandwidth and CPU for 5 million monthly page views which I think it is more than enough for a startup.

This is only a preview release of Google App Engine. For now, account registrations are limited to the first 10,000 developers, and applications are restricted to the free account limits. Go and grab your account now!

Requirements: -
Demo: http://code.google.com/appengine/
License: License Free