I'd rather see them like these here:
Again, this is not so much about the dimensions of the image but about the kbs. You could already do much by improving your graphics program. The franchise banner e.g. has >20 kb (still too big!), however if I save it with corel paint, it's less than 10 (acceptable).
Maybe we can just set the absolute limit for signature pics to 10kb? Some more input of modem and dialup folks would also be appreciated. Thanks!