You can learn more about the Sunbird application from the Mozilla foundation at www.mozilla.org/projects/calendar.

You can read more about WebDAV at www.webdav.org and about mod_dav for Apache 1.x at www.webdav.org/mod_dav. WebDAV support in Apache 2.0 is at httpd.apache.org/docs-2.0/mod/mod_dav.html.