The following MediaWiki extensions allow you to display a calendar within a wiki page:
- DPL Calendar - not actually an extension, but a set of templates that can be used in conjunction with any of the DynamicPageList extensions to display an HTML-based calendar. All events must be defined with pages that contain a date in their names. More information here.
- MsCalendar - displays a calendar of events, as well as a popup form to let users enter events. All event information is stored in the database, not in wiki pages.
- SimpleCalendar - displays a monthly calendar, with each day being a link to a wiki page. (No events displayed.)