micro_httpd is a very small Unix-based HTTP server. It runs from inetd, which means its performance is poor, but for low-traffic sites, it's quite adequate. It implements all the basic features of an HTTP server in only 150 lines of code.
Web Diary is a Web-based multi-user CGI diary applet. It is sortable, listable, and editable, and it includes scripts for allowing users to make entries publicly viewable, easy administration, and user preference editing.