A NationBuilder calendar lets you list upcoming events, search for nearby events, and display your events on a map.
It sorts events chronologically by default. You can switch it to be by distance, and choose whether or not to show a map. You can include a custom introduction and choose to allow user generated events with sub-menu settings, including assigning a point person to any event creators.
It also includes autoresponse emails. Read more about how to organize events with NationBuilder.