FWIW:
http://caer.me:2988/server.js
That's the source to the Node app that's serving the monitoring page.
Also, in the time between writing the above paragraph and starting to write this one, I rewrote a big chunk of both the monitoring, server and client-side code. The monitoring code now stores counts etc. in the database (previously it appended to a log file), while the server code now sends the data in a nicer format. The client code has been updated to take that into account, and is now simpler as a result.
Oh and
Redis is cool, you should try it. Much more lightweight and straightforward than *SQL.
edit:
oops, just noticed my MIME type thing is a bit stupid.
edit 2:
How come you're not requesting the graph data via AJAX? Seems a simpler way to do it, imo, and less for your server to do.
EDITED: 6 May 2013 21:22 by CAER