Used to be that people could email Ziroc and ask for a sig pic to be hosted, but I havent heard of anyone doing that in a while. Theres no advantage to it either, because you can use a free service like
www.ranchoweb.com to host pics. They have a high uptime, decent enough speed, and you can call the pic from anywhere, whereas calling a IW hosted pic from another forum or site is not permitted. (It probably works, but its bandwidth theft and hence illegal).