Whoisology - Connected database of whois records and whois history
GRC Port Scan - GRC Internet Security Port Scanner. Tests for open ports on your external IP address.
WhoisThisDomain - Domain name lookup tool that allows you to get information about domain registration from WHOIS server.
What is my IP? - Find out what your IP is. Do not hesitate to open wimip.
JSON WHOIS API - Parsed domain WHOIS data from any WHOIS server via RESTful API with metered pay as you pricing.
whatismyip.cc - External IP Address lookup tool with option to scan the external IP address.