If you haven't already seen it, check it out:
SHODAN - Computer Search Engine
It is more or less a search engine for servers--so a search engine of banner grabs--port 80, 21, 22, 23. Very cool.
A few examples:
SHODAN - Computer Search Engine -- 2,900+ still running IIS 4.0!
SHODAN - Computer Search Engine -- 67,000 Cisco web interfaces...
Refine by country code, hostname, port, and CIDR/IP range.
Created by @achillean (http://twitter.com/achillean), awesome tool.