In order to appear on the georgeous http://stats.ethdev.com monitor (AKA 'netstats'), you need to set yourself - it's a voluntary process. This means the dashboard represents only a small selection of nodes, not the entire network.
You'll need to go through the documentation, there are two documents:
Follow these instructions and the centralized netstats will have access to your info.
Note there is also a secret key to input and be accepted by netstat at the moment, called WS_SECRET. We're thinking of a public version, but right now, we're keeping the number of nodes pushing data to the monitoring server reasonnable - if you want to give it a shot and get the key, join the skype channel for netstats.
Note: The monitor was build by @cubedro (Marian Oancea) - I think it's fair to say he's done an amazing job!
Updates 15/05/2015 - updated screenshot 23/05/2015 - minor update 28/07/2015 - updated to reflect the new key distribution process 3/07/2015 - updated for Frontier