As its off topic I'm allowed to advertise: http://www.strongholdkingdoms.com/
Stronghold Kingdoms is a massively multi-player online real time strategy game with a Medieval castle building theme. It was developed by Firefly Studios and based upon their commercially successful and popular Stronghold series of games.
So before you look it up, send me a mail and I will invite you to the game (I get gifts!!!). I think you need steam also. The game itself is free. http://store.steampowered.com/