How to add a directory of people/businesses to my theme?

Interesting idea. If you need to be able to have users be members of the businesses and know a priori what they are so that an admin can add them, this is a test idea.

If you just want a list of these businesses, using a category, perhaps with a template, may be what you want to do. This way anyone could contribute new businesses. But you’d not be able for people to join the business.