Hmmm, not sure if it can be done in a banner, but it would be nice to match the IP of the client to the nearest monitor near that IP and then include that image like you said.
Or, is it possible to generate that image included with a link back to the home page, that would make a seperate banner obsolete, but then everyone can add his local monitor data, (or any other monitor) to a website and automatically links back to uradmonitor.com
This will also do magic to the google ranking when more and more people link back. 🙂
AND you can see in your webstats from where all the images are loaded and how many people have viewed them.