We had a sign made up by From The Forty, a company owned by the family of a coworker of mine. It turned a lot nicer than we had anticitpated. Selecting the right font was tough, but I think we picked a good one. It's 4' wide and 3' feet tall. The 2" thick white cedar is coated in spar urethane, and should offer many years of use.
Holly was really easy to work with (read: was really patient with us), and it only took a week to make. They've got a nice selection of pre-made signs at really nice prices, and they can make just about anything you can dream up. Go check out their site.