Distributing a website over a content delivery network is typically an expensive proposition, but since the release of the Google App Engine beta program, there’s an option for small to medium sized sites to easily distribute content on Google’s infrastructure. Putting the application SDK aside, Matt Riggott wrote a decent howto on using the service simply as a free CDN:

A content delivery network, or CDN, is a system of servers spread around the world, serving files from the nearest physical location. Instead of waiting for a file to find its way from a server farm in Silicon Valley 8,000 kilometres away, I can receive it from London, Dublin, or Paris, cutting down the time I wait. The big names — Google, Yahoo, Amazon, et al — use CDNs for their sites, but they’ve always been far too expensive for us mere mortals. Until now.

There’s a service out there ready for you to use as your very own CDN. You have the company’s blessing, you won’t need to write a line of code, and — best of all — it’s free.

There are limitations to the service, of course. You can’t host any files larger than 1MB, and you’re limited to 650,000 requests a day and 10GB of downloads. That said, there are a lot of sites that fit within these parameters and could offload the static portion of their content to see a large reduction in bandwidth and provide faster load times to end users.

Using Google App Engine as Your Own Content Delivery Network
Google App Engine