Wow, I like the solution you described monk.e.boy. I could have a php page, serveImage.php, that takes in some url arguments like the path to the image, and then write the appropriate images headers to send the image back. I wonder what kind of effects this will have on the browser experience and other parts of my website. I'll try to implement this and post if there were any drawbacks or anything I can't think of now. Thanks again for the solution.
Thanks mbtaylor for your suggestion, but that is not what I want to do as I said in my first post on this thread. That tutorial shows you how to ask the user for HTTP authentication credentials with PHP. I do not want to prompt the user for these credentials. But according to monk.e.boy, I won't even need to use HTTP authentication.
And I believe the solution you provided, ShogunWarrior, is similar to monk.e.boy's.
Could this also be a solution for the hot-linking problem?