enigma1 - 9:09 am on May 28, 2009 (gmt 0)

darkage, best to have the users upload the images, then you validate/authorize them before displaying. Or maybe you can have instructions to upload their images on another server which you trust (there are services online for this I believe) and then have your server to automatically download them and store them.

But if you have your server to automatically downloads them, stores them and then are accessible without validation is no different than the hot-linking problems mentioned above.