iana.org
IANA database listing top-level domains, registry operators, and root zone delegation data.
Directory
Search results
Published directory entries matching your search.
pentest-tools.com
uses advanced search operators (Google Dorks) to find juicy information about target websites.
exonerator.torproject.org
A database of IP addresses that have been part of the Tor network. It answers the question whether there was a Tor relay running on a given IP address