mpo2png is a small tool made by Kawa in a fit of inspired boredom. It takes a .mpo file as saved by the 3DS camera and turns it into a single anaglyph image in PNG format.
An earlier version had the left and right sides reversed, due to a lack of glasses and incorrect guesswork. Roxahris noticed the problem, and a fixed version has been made.
mpo2png foo.mpo yields foo.png mpo2png foo.mpo bar.png yields bar.png
MPO files are basically two JPG images stuck together, one for each eye. That's all there really is to say on the matter.