Philadelphia Baduk Association
The Philadelphia Baduk Association is a Korean club in North Philadelphia. Their website is here.
Imagist: I play here often. The vast majority of the players are immigrants from Korea, so it's a great place to gain experience playing a fighting game. The average strength of the players is somewhere around 1 or 2 dan AGA, which I guess would make it one of the stronger clubs in the US. There are also a number of extremely strong players who are often willing to play games.