I am not sure if I am using right name of "Categories" since I could not find what I am lookig for in plugins.
What I want is: I have a multisite with single domain, when people register a blog on my page I want them to specify what category their blog belongs to. And on the front page of my domain, I want to have a listing of all registered blogs by category. Same thing what they have on this page on left hand side:
Thank for your help