I run one of the hundreds of stupid "what is my IP" websites out there. For about the past month, I've been receiving about 500 hits per hour, from distinct IP addresses, using a miscapitalized Googlebot user-agent:
Mozilla/5.0 (compatible; googlebot/2.1; +http://www.google.com/bot.html)
Many of these seem to be from Russia, but enough have unique reverse DNS entries that suggests these sites may be hosting content. I suspect this is a botnet of some sort.
Any ideas on how to proceed?