Our club serves at the Shreveport Beer Fest where we are one of approx 15 commercial and homebrew groups. Capacity at the event is 1600 people.
At the 2009 fest we had 3 servers and served 65 gallons in 3 1/2 hours.
At the 2010 fest we had 11 servers and served 85 gallons in 3 1/2 hours.
This year we're bringing 110 plus gallons consisting of 21 different brews.
We found out real quick that if you want to keep the line moving you need to serve from pitchers. It's probably going to be loud, and you don't want to have to ask for Dindlewiddle's Chocolate Cheesecake Raspberry Stout over the noise, so mark each pitcher and keg with the number and the name of the brew. When your server runs low on beer he passes the pitcher back to one of the fillers. Station 2 or 3 gas men behind your cornys to charge the kegs when they get low.
In 2009 we used trash cans and a kegerator to ice the beer. In 2010 we iced the kegs down in a horse trough. That worked a lot better, and it cleaned up our back line so we weren't tripping over each other.
Good Luck!
Charlie