[@_ck_ Participant 17 years, 1 month ago]

This indeed is a very tricky problem because everything about a browser’s security is designed to prevent this from happening.

WordPress.com addresses it in one possible way (across multiple domain names) via I believe a hidden iframe (as Sam suggests).

I’ve noticed cookies are still sent with images loaded from another domain so that might be another way but you’ll still not be able to read them on the server since it’s not the local domain.