aggregator/reblogger, is this possible?

i would like a web-based aggregator that allowed me to re-post something to my main blog. in other words, i would have a page of other blogs and clicking “add to my blog” next to any post would offer me some options to post the same content to my blog. ideally, it would slurp down their images and store them in a local directory (for courtesy to their bandwidth) and append a “via (sitename.com) to the bottom of the post. i imagine it would copy the main blog text into a text field so additional comments could be added.
has this been done, and is this possible without too much trouble?