I am currently working on combining content management systems with mapping.
You may add maps to your site by using easy to use mappingAPIs from Google and Yahoo.
Content management systems provide applications that are
used to manage items like
news stories, blogs, forums, etc. They also provide other things such as
user management, and templates that provide a certain look.
Mapserver - Open Source development environment for constructing spatially enabled Internet-web applications
Ka-Map - A project aimed at
providing a javascript API
for developing highly interactive web-mapping interfaces.
Google Maps API - used to create highly interactive web-mapping interfaces using Asynchronous JavaScript. Pretty easy to use.
Yahoo Maps API - used to create highly interactive web-mapping interfaces. Very sophisticated. Three interfaces to choose from.
Content Management Systems
Here are some content management systems available on the web.
Xoops - My favorite. The good: Very easy to install and easy to understand. The bad: they've been promising a new version for quite a while now and development seems to be very slow.
Mambo a.k.a. Joomla- Seems like it has more capabilities than Xoops, but is somewhat more complicated.
Drupal - Simple, and quickly growing in popularity.