TwitterVision which tracks all the recent Tweets from users - see our series on Twitter for more info.
A more obvious application for real-time mapping are visitors to a site and now that is possible using the service from Statisfied. It is easy to set up, you simple register a user name and then copy a section of code into your sites header - this works in both Blogger, WordPress and general html based sites.
The results are fascinating - it is almost a feature that you can leave running on a second machine and sit back and watch. Our stats are minimal to be honest, although growing slowly, but if you take a look at our real-time site visitors page you will note that it caches the last 5 or so readers, your current location will be the last one displayed:
View your location on our live sites visitors map (click the red cross if you get a register window - this will then take you direct to our map)
Depending on our level of traffic a new visitor should pop up every minute or so.
Visit Statisfied to set up your own real-time stats.