There are several calendar plugins for WordPress. You can find most of these plugins using the WordPress Plugin Directory Calendar tag.
This event manager attracted my attention with a few cool features. It has Google maps integration, an RSVP mechanism and recurring events.
This calendar has a nice look, but it is lacking recurring events. It is hard to convince churches that Sunday Service needs to be added to the calendar each week. Of course, one could argue that if it is truly a standard weekly event it may not need to be on a calendar. I don’t know which way I fall yet…I can argue both ways.
I like this calendar because it can use a Google Calendar. I don’t always convince users that Google Aps is the way to go, but when I do this is a great option. For those using a different calendar program, this plugin works with most common calendar programs.