This simple Chrome extension shows your external IP and then uses uses the IPInfoDB API to provide geolocation data, based on that IP. You can download the extension from the Chrome app store.
This extension makes one call to a server side, that uses IPInfoDB to turn the IP into a result JSON.
You can read the whole story on my blog, and find the server-side source at https://github.com/TravelingTechGuy/myip.
Created by Guy Vider, Traveling Tech Guy (c) 2013