http://instasrc.com/400x400 or http://instasrc.com/400/400
http://instasrc.com/400x400 or http://instasrc.com/400/400
http://instasrc.com/400x400/art or http://instasrc.com/400/400/art/greyscale
http://instasrc.com/[widthxheight]/[category]/[effect: normal or greyscale]/[optional: new ]