Soccersmylife, I don't know of a web page that lists all referees. However, at USSoccer.com under the referee tab you can get e-mail addresses for all state referee administrators.
Chico, several people are using the Arbiter system. Thing is it's kind of being district run, meaning, there is a group for the low country, a group for the upstate, and I don't know if mid state is using one or not. It's a league/tournament choice who assigns their respective matches.
It's not enough to go and get the training, and sit back and wait for the call. You have to know who assigns what, and work through it. In the Charleston area, there are basically 4 assignors that can get all the matches you ever need, rec, classic, challenge, tournaments, and HS (which is a separate certification).