TrueIP - TrueIP is a small program that runs in the system tray, monitoring your IP address(es).
What is my IP? - Find out what your IP is. Do not hesitate to open wimip.
GRC Port Scan - GRC Internet Security Port Scanner. Tests for open ports on your external IP address.
ShowIP - ShowIP displays the IP address(es) of the current page in the status bar.
geoiplookup.net - (IPv4 only) Online tool to get accurate IP address information
whatismyip.cc - External IP Address lookup tool with option to scan the external IP address.