Obviously, there are a ton of guestbooks out there. JonBoard is intended to be a simple to install little tool -- it creates all the files it needs and requires no special scripting ability, nor does one need one of them high fallutin' SQL servers...
Classic Guestbook Made With Flash - Php is multi-platform compatible. Its an example of classic guestbook. Data will be displayed in flash movie in HTML format.
Simple guestbook is a Unix compatible script that allows visitors to your site to read your guestbook entries and post a message of their own. Very simple setup, only requires you to change 4 settings. Uses MySQL to store the entries.
Micro guestbook is a MySQL based guestbook script with a CSS based attractive interface. It can store the name, date, message, location, web and email information of the visitor.