Guestbook is closed down and locked by Password - it was only missused for WikiSPAM. In the end we had to clean SPAM and SPAM-bot testing twice a day.
It is a sad truth that the Spammers will mercieless destroy everything what is good about the Internet. Even as it is a complete waste of time as all external links need aproval and maked "nofollow". But SPAMmers are by far to stupid to understand those finer part of the Web.