Event Calendar!
The Comunity Calendar extension allows you to quickly and easily tag your Forum Posts, File Gallery Files, Weblog Entries, and Gallery Photos to show up on the calendar below.
Simply add a tag like [cal]1-1-2006[/cal] to your post ( where 1-1-2006 is the date of your event ) and if the user has permission to view your post, a link will appear in the calendar below for them to see.