tedster - 5:51 pm on Jul 1, 2010 (gmt 0)
I like the ip: operator:
Finds sites that are hosted by a specific IP address. The IP address must be a dotted quad address. Type the ip: keyword, followed by the IP address of the website.
Prefix-matching is also possible, that is, ip:46 would return the site IP:18.104.22.168 if the latter is in the index.