I have a created a small library for making this work even easier: GitHub - sfentress/ArduinoEthernetCom: Simple communication between an Arduino and the browser using an Ethernet connection
Now you can create basic examples of getting data from an Arduino with about 10 lines of JavaScript. You can look at the source of the example page at http://sfentress.github.com/ArduinoEthernetCom/example.html