One Pica ImageCDN Magento extension
This extension enables you to host category and product images on a separate server with ease. This can improve page load time by offloading some of the stress from your web server and by allowing you to utilize a high performance content delivery network (CDN) or another remote host. If your website has a large amount of traffic, using a CDN will help to bring down your bandwidth cost and speed up your response time. Currently, the extension integrates with Amazon S3, Coral CDN, Mosso/Rackspace Cloud Files, and any CDN, server or service that supports FTP, FTPS, or SFTP. Each adapter has a separate configuration menu with options unique to each. The abstract adapter can be extended to easily add support for any other CDN that has a published API. In this respect, we are always seeking new CDNs to include in this extension as well as community-provided implementations to be added.
See the extension on Magento Connect for more information.