TrueIP - TrueIP is a small program that runs in the system tray, monitoring your IP address(es).
whatismyip.cc - External IP Address lookup tool with option to scan the external IP address.
My Public IP - My Public IP is a utility to let you know through which internet IP the world see you.
GRC Port Scan - GRC Internet Security Port Scanner. Tests for open ports on your external IP address.
IP-Toolbox.com - IP-Toolbox.com is the best site for quick and easy viewing of your public IP address and other related information.
geoiplookup.net - (IPv4 only) Online tool to get accurate IP address information