Found this in the logs today:
54.245.0.nnn - - "GET / HTTP/1.1" 301 - "-" "Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.9) Gecko/20100824 Firefox/3.6.9"
IP belongs to Amazon Technologies. Ranges are:
54.245.0.0 - 54.245.255.255
54.245.0.0/16
Did a search on webmasterworld site, but didn't see this one, so just passing this along.