Web Droppings (The Web)
Typography Basics: Typeface Classifications
To create a good typographic layout, you need to know when to use and when not to use different styles of type. It is, therefore, important to understand the differences between typeface classifications.
Of course, this is a much better classification scheme than my personal one, but mine makes good sense to me ;) I think that slab serif is the one that is hardest for me to classify, since they are still serifs; I tend to put them all in serif.