As in on this site? Well, in my own realm I know most of the decent debaters, and how they debate. I also know how badly they can beat me on certain things, and the other way around, as it goes.
But in terms of my friends, maybe Manta and Moat. I also got to know Firetail pretty well. A couple others, too. That's 'bout it. I don't talk to many people.