YapGB is a free guestbook written in PHP, relesed under the terms of the GNU GPL license. Its features are: - No database needed, just a plain text file. - Admin interface for editing/deleting entries. - Fully customizable appearance through a theme system. - Custom timezone. - Notification of new entries. - Smilies and BBCode support. - Moderation queue. - Option to require the user to enter a confirmation code when signing the guestbook. - Email and URL links are optionally shown to visitors, they're always shown to administrator. - System messages (mainly erros) are easily customized/translated. - UTF-8 character set (also available an ANSI version).