Thingful!

SHODAN is a search engine that lets you find specific computers (routers, servers, etc.) using a variety of filters. Some have also described it as a public port scan directory or a search engine of banners.

IVRE, a network recon framework.

PunkSPIDER is a global-reaching web application vulnerability search engine. The goal is to allow the user to determine vulnerabilities across the Internet quickly, easily, and intuitively.

Censys is a search engine that enables researchers to ask questions about the hosts and networks that compose the Internet. Censys collects data on hosts and websites through daily ZMap and ZGrab scans of the IPv4 address space, in turn maintaining a database of how hosts and websites are configured. Researchers can interact with this data through a search interface, report builder, and SQL engine.

ZoomEye is a search engine for Cyberspace