See <a href="http://www.madore.org/~david/computers/quine.html" rel="nofollow">http://www.madore.org/~david/computers/quine.html</a> and <a href="http://www.nyx.net/~gthompso/quine.htm" rel="nofollow">http://www.nyx.net/~gthompso/quine.htm</a>
I once wrote a gimp script which would create a black and white image (I think 120x120), which produced the original source code when read as a binary string.