Adafruit 94 Wave Shield for Arduino Kit can play up to 22KHz 12bit uncompressed audio files of any length. This shield includes an onboard DAC, filter, and op-amp for high-quality output. The wave shield features mono output, L and R channels, standard 3.5mm headphone jack, and speaker connection that is switched on when the headphones are unplugged. This 94 wave shield works fine using any ATmega328-based Arduino.
Can play up to 22KHz 12bit uncompressed audio files of any length
L and R channels
3.5mm headphone jack
Requires 10k of flash and more than 1/2 K of RAM for buffering audio