There is a good module imageache external that creates variants of images from external links, it's in sort of API mode as you have to code to use it. Also for purpose of FBSMP module I am using with it and better SEO, I changed how it works and made it possible to have image filename correspond to status which is third parametar in
function imagecache_external_generate_path($url, $preset, $name_img) {this third parametar is adde by me and the rest, well u can find it in zip below and check differences with http://diffchecker.com/