Here's one I've always thought was cool, from my early days as a Commodore 64 programmer. It's pretty easy to do, I just convert to grayscale at the desired resolution then convert to ASCII chars used to represent shading values. Need to fine tune it a bit more, do things like figure the min/max shading value, set transparent GIFs' backgrounds to white, etc but what the heck. I did this one at 11 o'clock at night on a Saturday after having a bit to drink. :s