OCModShop tested a free WOW server that seems to work well and keeps you from having to pay the subscription fee.

Quote: "But one game heralded the age of MMORPG, and still remains at the top. The World of Warcraft. It has the power to engulf your mind in a world of fantasy creatures and fantastic worlds. With several races to choose from and over a million players from around the world logging in to battle, Warcraft has staked its claim as the leader in online gaming. And you too can experience their World, for a mere $15.00 per month, plus the cost of the game. Unless, that is, you are one of the thousands of people who are members of WoWscape.net."
Read the full report on OCModShop.