Streaming Arduino Data to a Browser without Flash or Java
https://blog.concord.org/streaming-arduino-data-to-a-browser
You have to have an Arduino with an ethernet shield and connect it directly to your computer.
He's using the simple grapher I created using D3 and integrated with NetLogo here:
http://stepheneb.github.com/netlogo-gcc/index.html
https://github.com/stepheneb/netlogo-gcc
Interested developers check out more technical details on this thread on the org-concord-sensor email list:
http://groups.google.com/group/org-concord-sensor/browse_thread/thread/80602532466a8593