I set up one of the servers we're using for the happening and added to it Browser monitoring. This collects many statistics useful for improving modern browser based websites. website 
Happening page views from around the world. See report
The most useful result for me so far has been collecting tracebacks from exceptions thrown in federated wiki client code running in your browser. I've seen two so far. One error is still under investigation.
I also get reports tallying were in the world my server is used. Keep in mind that this report is for only one of the happening servers and that a page view just starts an interaction with the whole federation. report