Recently, I am searching for multi servo controller (12+ servos) for arduino and I found those boards online and seems they all have both good and bad side depends on your purpose of uses. I was planning to build a multi leg bots with remote control and I think some of these arduino boards has all-in-one stuff like bluetooth, xbee etc.
Some of the products in following links may found on eBay for cheaper price but you can get basic info from there.
Arduino USB SSC-32 Servo Motors Controller with Bluetooth
http://www.bizoner.com/arduino-usb-ssc32-servo-motors-controller-with-bluetooth-apc220-p-215.html
This one is base on SSC-32 from lynxmotion I think. It support up to 32 servos with 2 external power supply(16 per each). I have my hexapod with SSC-32 and it was pretty good but don't know if this Arduino version is good as original.
Arduino All-in-One Controller - RoMeo
http://www.seeedstudio.com/depot/renbotics-servoshield-rev-11-p-498.html?cPath=78
This is well known board RoMeo has multi build-in stuff.
Renbotics ServoShield Rev 1.1
http://www.seeedstudio.com/depot/renbotics-servoshield-rev-11-p-498.html?cPath=78
I accidently killed one of this board and 2 4017s burned. The board seems pretty simple but some forum doesn't recommand this one for some reason.
Arduino Duemilanove IO Expansion Shield, Xbee Bluetooth SD Card
http://www.bizoner.com/arduino-duemilanove-io-expansion-shield-xbee-bluetooth-sd-card-p-208.html
I got one of this on the way here and it has external power for servo control plus Xbee and other I/O support.
Arduino MEGA IO Expansion Shield Support Xbee,I2C/TWI,SD Card
http://www.bizoner.com/arduino-mega-io-expansion-shield-support-xbeei2ctwisd-card-p-224.html
This is for Arduino Mega plus xbee support
Arduino Nano Expansion Shield Compatible
http://www.bizoner.com/arduino-nano-expansion-shield-compatible-with-nano-v2x-v3x-p-199.html
Nano version - I haven't use nano bofore. So, just FYI.