Amazon.com just announced that one can host static web sites in a S3 bucket. I went to their setup page at http://docs.amazonwebservices.com/AmazonS3/latest/dev/index.html?W
How about using a DNS service, like the Route 53 that Amazon provides. Set it up with a CNAME from your sub domain to the public bucket URL. Of course, if your domain company provide CNAME configuration, that could work directly.