The Bessatsu magazine xxxHolic survey is up and running. It will ask you things like your favorite character, couple, scene and to write a message to CLAMP. I think this information will be used in the upcoming guidebook. If you have a Japanese address, you will be submitted to win a QUO card with the xxxHolic Complete Guide's cover illustration. 100 applicants will be chosen.
Even though you must fill out the address to get your answers submitted and you live overseas, if you want your thoughts about xxxHolic to be heard, go for it.