Wifi for Arduino

I would like to fit WiFi and Web Server capabilities to an externally mounted Arduino to enable it to upload data itself to a website without the use of a PC. i.e. the device must be recognisable by a wifi router nad have it's own IP address.

I know that Little Bird Brain do a WiFi shield, but at $245 that is WAAAYYYY too expensive. Has anyone done anything like this before for a reasonable cost?

I was just looking at this:
http://www.geocities.jp/arduino_diecimila/wifi/index_en.html

Never tried it though, not sure about setting it up, etc.

Excellent. Might be just what I am looking for. Thanks