What is my IP? - Find out what your IP is. Do not hesitate to open wimip.
TrueIP - TrueIP is a small program that runs in the system tray, monitoring your IP address(es).
GRC Port Scan - GRC Internet Security Port Scanner. Tests for open ports on your external IP address.
geoiplookup.net - (IPv4 only) Online tool to get accurate IP address information
My Public IP - My Public IP is a utility to let you know through which internet IP the world see you.
whatismyip.cc - External IP Address lookup tool with option to scan the external IP address.