An article Plug-in?

OK, what I want is the following.

A list of categories

The user can click on a category to display a list of articles.

The article would then look very much like a single blog entry with ability for users to comment.

Now.. before I build this myself I was wondering if there is anything about which will already let me do this. I want to keep my ability to blog as well as write articles. I do not want these articles to show up in my blog list.