[Plugin: NextGEN Gallery] WP image update from external URL?

I want to update an image in a NETXGEN Gallery from an image on an external URL.

I know this is outside the scope of what the NG plugin does. I’m wondering if someone knows of a plugin for fetching an external image and stuffing it into a specified file. Obviously, I’d fetch from a URL and save it into the path/filename of an existing NG image file. I don’t care about updating the thumbnail.

I know I can easily do this outside WordPress with a cron job invoking wget or curl. But I’m hoping for a WP plugin which will give a WP admin the ability to keep the configuration updated.

http://wordpress.org/extend/plugins/nextgen-gallery/