QF-GetThumb is plugin to make the thumbnail and the cache of first image data in the content and the argument source.This plugin can make JPEG, GIF, a format of PNG, And makes the image of not only a local server but also the outside link a thumbnail and can become cache.
Outside RSS can be read depending on the application.
"The image of the article published in other blogs is read to my blog" Applied technique can be done.
Demonstration site is here!!