Guest book-related web-based apps. A web guestbook (also guest book, visitor log, visitors' book, visitors' album) is a means for a visitor to acknowledge a visit to a website, and leave details such as their name, postal or electronic address and any comments. These apps are designed for this purpose.

Advanced Guestbook is a PHP-based guestbook script. It includes many useful features such as preview, templates, e-mail notification, picture upload, page spanning , html tags handling, smilies, advanced guestbook codes and language support. The admin script lets you modify, view, and delete messages.
BellaBook is a small and simple PHP guestbook. It works using "flat files" - that means no need to fiddle with complex MySQL databases! BellaBook has been crafted to provide a feature packed user feedback system with an easy-to-edit coding structure; using CSS to control it all.
Lazarus is a free guestbook script written in PHP that uses your MySQL database for storage and is based upon the excellent Advanced Guestbook script from Proxy2. Lazarus has more features and several layers of anti spam protection to make one of the most feature rich and spam resistant guestbook scripts available for free.
PHP Address Book is a Simple, web-based address & phone book based on PHP and MySQL.
phpBook is a PHP/MySQL guestbook program. Features: Nice interface; Fast and stable code; Language templates (english, german, italian, potuguese, french, dutch, swedish, chinese, japanese, danish, etc); Location templates (world, europe, belgium, etc); IP logging and banning; Browser logging; Pagebreak's; Smilie's database and help (over 90 included), etc.
PHPKode Guestbook is a simple yet powerful Free PHP guestbook script using Ajax. The Guestbook features for easy to install, easy to integrate into your existing sites and an advanced anti-spam function. PHPKode Guestbook uses the Captcha image as the way to anti-SPAM protection. IP banlist is also provided to prevent admins from being spam.
RicarGBooK is a guestbook system written in PHP and based on flat files. You can delete or modify any comment with an admin control panel. It's easy, simple and completely free!
VX Guestbook - Allows you to add free guestbook to your site. Easy to install and use. Editable with template.