Good questbook! But I'm Polish user and for users from my country it is not fully functionality. Why? In my country verry popular is one online communicator. It is Gada Gadu (www.gadu-gadu.pl). It is verry important for me and my site users to see questbook users GG statuses! :) of course it is fun, but more functionality for Your Questbook is good idea! :)
Best Regards!