Developer website: ACal Project
ACal Calendar is a Web based event calendar that does not require a database server. It is made to be easy to install and to be able to run on just about any typical ISP's server with PHP installed.
Version 3.0a3: Many bug fixes, email event notifications, potential Windows support in event notifications, a new Mac OS X installer for Tiger.
Mac OS X 10.3 or later, PHP 5.0.0 or later,Apache 1.3 or later