This is quite handy:
http://arduinodrums.blogspot.com/201...d74hc4067.html
Basically you buy an Arduino and one of these: http://www.sparkfun.com/products/9056 ($4.95) and you instantly get 16 analogue pots. The good thing about this mux pcb is that its really cheap and you can use multiple mux's... 64 pots should be feasible, if you're using an Arduino Mega, for less than £50 in total (if you buy an Arduino Mega clone for £20 like I did!)