http://code.google.com/appengine/

Run your web applications on Google's infrastructure.

Google App Engine enables you to build web applications on the same scalable systems that power Google applications.

No assembly required.

Google App Engine provides a fully-integrated application environment.

It's easy to scale.

Google App Engine makes it easy to build scalable applications that grow from one user to millions of users without infrastructure headaches.

It's free to get started.

Every Google App Engine application can use up to 500MB of persistent storage and enough bandwidth and CPU for 5 million monthly page views.