Convert linked photos to attachments

[Pottsy]

I'd love a mod that allows a moderator or admin to (in one click or so) convert all images in a post that are on an external server and linked using [img] tags, to attachments on your own server.

Each image would be downloaded from the external site, and then popped into the post in the correct place using the [attach]xxx[/attach] tags.

This would have the following advantages:

Better load times (imageshack can be really slow).
When a user deletes those great and useful photos, they don't vanish from your forum.
If you are disallowing guests from seeing image attachments, then this is upheld.

Just a thought...