You could be looking for a content management system or CMS.
Wendy Piersall, a fellow member of the LinkedIn Bloggers group has a blog eMoms at Home which is dedicated, as the name suggests, to helping mothers who want to start, run and succeed in their home based business.
Wendy has been on a search for an open source content management system or CMS that would meet her fairly exacting requirements for another of her websites and her post Building a Site: Using and Choosing a CMS should be a useful reference for others contemplating a similar search. Having done some searching along these lines a couple of months ago, it looks to me as if Wendy has been very thorough and has some very useful observations to make.
She promises to provide progress reports on her installation and development of her chosen product, Joomla!
Rant alert: By the way, I wish companies wouldn’t name products with Exclamation Marks! For one thing, it prompts some word processors to start the next word with a capital letter! For another, my blogging software won’t let me use a word with an exclamation mark as a keyword.