Calendars

The following MediaWiki extensions allow you to display a calendar within a wiki page:

Cargo - displays a JavaScript-based calendar, showing events that match any particular query. Events can be color-coded by type. Pages defining events must use a Cargo-tagged infobox template, a process made easier with the use of the Page Forms extension. Cargo can also generate icalendar feeds for subscribing in external calendar clients.
JsCalendar - displays a JavaScript-based calendar. All events must be defined with pages in the "Event:" namespace, with the date of the event in their name. Features include keywords-based and category-based coloring and HTML snippets of events. Only MySQL is supported.
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.
Semantic MediaWiki + Semantic Result Formats - can be used together to display both HTML-based and JavaScript-based calendars. Together with the Semantic Compound Queries extension, events can also be color-coded. Pages defining events must be encoded with tags to indicate their date(s), a process made easier with the use of templates and the Page Forms extension.
SimpleCalendar - displays a monthly calendar, with each day being a link to a wiki page. (No events displayed.)
Widgets - lets you embed a Google Calendar using the Google Calendar widget.
Calendar-Wikivoyage - used on Wikivoyage wikis and the extension stored in the Gerrit repo mediawiki/extensions/Calendar.