WaveShield

is a DIY Kit designed by Ladyada from Adafruit Industries that, together with an Arduino compatible board, will allow you play uncompressed WAV files from an SD card. The files can be recorded in different qualities (8 or 16bits, up to 22KHz).

There is plenty of documentation about this item at Ladyada's website. You can prototype your installations with this kit and, make final products with the Smaper v0001.