well, there's svg) as for raster, first, I don't think you can have infinite sizes as in vector in feasible manner, second, progressive jpegs are already there,

well, there's svg) as for raster, first, I don't think you can have infinite sizes as in vector in feasible manner, second, progressive jpegs are already there, maybe we need to teach clients to stop downloading more info when there's enough for certain container.