Globe*Trotter is a guestmap. It allows Web site visitors to mark where they live on a map and include their personal comments, instead of merely tacking their personal regards onto the end of a long list. It benefits your visitors because they can easily read other's comments and add their remarks in a fun and novel way. It also benefits you, the webmaster, because more people will be likely to give you feedback and you will be able to see where your visitors are. A free hosted version of Globe*Trotter (with no ads) is available.
KISGB is an advanced PHP guestbook program that does not require sessions, cookies, or an rdbms. It can be public or private through HTTP authentication. Features include message preview, message editing by users, a theme builder, private messaging, flexible logging capability, a Web-based password protected admin section, email notification, IP logging, IP banning, a bad word filter, smileys, automatic link recognition, flood control, support for 29 languages, and much more.