Here is an example of the CMS Drupal. It was built for girl scouts and allows for easy content editing. They have the ability to manage a calendar for others to see and organize events, upload photos to a photo gallery, and create pages with the ability to comment, or not whichever you specify.

This was a very easy quickly put together and cost-effective web site. If you are interested in a site like this I would love to help you. These are great for any local organization or even just a group of people.