I just started playing around with the Visualization API today and it's pretty cool. Here's a short screencast I just did showing real-time power usage from our Brultech ECM-1240 power monitor. Every second, data from the ECM-1240 is stored in MySQL. The gauges are in a simple HTML page with a little AJAX to fetch the power data each second from MySQL. The API takes care of the graphics and updating them.