Arduino: wifi parameters

I'm currently working on a project with Arduino and a Wishield (asynclabs model), that involves multiple users, user ids etc: Changing the color of a lamp by connecting to a webserver on the internet: Webpage processes all the info, and prints a .php file with only the color to apply to the lamp. Arduino gets that info and changes the color.

I was wondering if there was a way for a non experienced user to set the wifi parameters with a user interface (local ip, router ip, ssid, password...) without ever having to touch the code on the arduino program. I mean can i save the parameters in different variables, save the in the arduino memory, so it can be able to connect to the local wifi?

Seems impossible but if anyone has an idea it would be really great.