How would you like to scan millions of hosts on the Internet and catalog all the interesting insights? This is exactly what Fyodor, the author of Nmap or Network Mapper did last summer. Thankfully, he then went on to share his finding with the community at Defcon 16 in his talk titled "Nmap: Scanning the Internet". Interestingly, as Fyodor notes in his talk that scanning such a large set of IP addresses did help him in uncovering many bugs in Nmap and also forced him to make enhancements and add new features to make the scanner really fast. This video contains the entire Defcon 16 talk:

Scanning the Internet with Nmap (Defcon 16) Tutorial (http://securitytube.net/Scanning-the-Internet-with-Nmap-(Defcon-16)-video.aspx)