What if I'm a link spammer, then I'd love to have google's list. How can the list be more extensive than google? That is verifiably false. For example, generate a list of IP addresses(500,000+) that have the following characteristics:

1. Have websites that been indexed by google with a PR 2+.

2. Run Web Servers

3. Bonus Points if you can tell me which web servers run the most PR 2+ sites.

Now hopefully you can see how useful this list would be! I don't think nmap will do that for you.