MetaSynth plays pictures as sound. 

For a pixel, apply these mappings:
	''x-coordinate'':	point in time at which to make a sound
	''y-coordinate'':	pitch at which to make a sound
	''luminance'':	volume
	''red'':	left stereo component
	''green'':	right stereo component
	''blue'':	ignored (used to add "comments")

A third dimention not shown in the picture assignes a voice to each pixel: sine wave, wavetable syth, fm synth or sample.

MetaSynth provides painting package functionality to edit bitmaps, and will perform musically sensible transformations of various kinds. It will sample sounds (the pictures generated by speech are fascinating!), has software FM and wavetable synthesis built in. One of the examples is a short piece of Bach: you can see the melodic lines intertwining to form harmonies right there in the picture! 

There's a free demo available, and loads more information at[1].