A content management that makes managing a breeze for everyone so geeks are not a bottleneck for content. And the architecture makes URLs that are elegant, blows away the silliness that relational database driven web sites spawn, and makes complying with standards painless.
This web site is powered by Plone. Insanely simple to add content, complies with standards automatically, built for accessibility and multiple languages from the ground up, uses a clever AJAX feature set, gives enterprises the chance to use their own security login system, and build sophisticated applications with Plone as base using UML.
Built in RSS.
All web pages are valid XHTML.
Built in search.
Object database that allows on the fly new sections.
Oh yes, it's free.
Once other web content management programs catch up, then web site content could be ported with URLs intact between different web content management tools.
Run screaming from anyone who wants to sell you a web site with web addresses that use database calls (security disaster) in the URL. In other words if the URLs include any of the following you are making a mistake: .php .asp .aspx .do .jsp .cfm .