http://www.seeedstudio.com/depot/sd-card-shield-for-arduino-v21-p-492.html?cPath=104_109
SparkFun SD/MMC Card Breakout - BOB-12941 - SparkFun Electronics
http://www.sparkfun.com/commerce/product_info.php?products_id=9802
http://www.arduino.cc/playground/Learning/SDMMC
http://blushingboy.net/p/SDuFAT/