I got a bit of time to play with this again.
Now the webserver code calls the details from a mySQL database for each Arduino and then for each pin being used in each Arduino.
This effectively allows you to control as many pins as you want on any number of Arduinos , only limited by your IP addresses and patience to enter them all in.
Updated blog post with the details of the database and the revised PHP code.
WARNING: The PHP code is very much first pass. There are lots of areas it could be improved. But while I'm working on it, it makes sense to me.
Next step is to code a few pages to allow the adding/removing of Arduino and Pins without having to resort to mySqlAdmin. Once done I need to figure out how to get the status of the pins from the webserver running on the Arduino. The examples I have seen for the ENC28J60 have been presenting a PROGMEM page, so cannot be modified once the code has started.
All the fun...