Hey JSTurf, This is Linda, herotness, and I think the problem with your question might be that someone here has to have built a directory site using Wordpress in order to answer it.
Wordpress isn't specifically a platform you'd choose for a business directory, so I'm guessing that's why all the 'empty air'.
Here's a link that might be helpful to you. It's not something I've personally tried, but it can give you some direction anyway.
How to make a directory website (like JustTweetIt.com) using WordPress - Crane Factory. The actual directory is here:
Just Tweet It » THE Directory for Twitter Users!
Good luck!
Linda
herotness