AJAX Calendar is a plugin that will display an AJAXified WordPress calendar, include future posts for usage in event calendar. This enhances the functionality of the standard calendar by:
Allowing the asynchronous navigation of months, without updating the page
Added to blog as a widget
displays future posts and includes query filters to allow display of posts even for planified/ future posts
link to month archive
display filter ajax_calendar_future_calendar_after can be used to add theme specific content below the calendar, like a google map of event (check out tiarvro.org for demo)
documentation and plugin details : http://www.webmasterbulletin.net/wordpress-plugin-ajax-calendar-with-future-posts
this plugin is the basis for our WPFESTIVAL theme development project : http://wpfestival.com. Bring your suggestions !
Documentation
Full documentation can be found on the AJAX Calendar page.