I know this is not really what a microcontroller is for but...
Would this work:
convert a small wav file to an array of 8 bit ints
embed that array into an arduino program which sends the values out
via a function like freq_out()http://www.arduino.cc/playground/Main/Freqout
I would just try it myself but it's turning out to be harder than I thought to find something to create
the int array so I figured I'd ask if anyone thinks this would work before I go to all the trouble of likely
writing a little program to do the conversion for me.