This and what the couple of posts above mention was really what I was alluding to when talking about a directory being a site the same as any other.
One can think of a directory in the "classic" definition - in other words, a collection of links to other sites. But what and how much you add to that, and the way that you chop and slice it, *is* your brand.
I've done sites in topical and niche areas that you possibly would call websites. I would call them directories because that is fundamentally what they are. But they focus on what the potential user base of that niche wants to know and how they want to know it, whether it is factual, geographical, visual, user-contributed or expert-led.
For example, on one site/directory I have certain types of image that are highly useful and interesting to the user-base. They require a knowledge of the niche and are difficult for others to replicate without the same amount of knowledge and work. One of my upcoming projects is to add relevant video to the site. But it doesn't make it any less a directory in my eyes. (Or does it?)