Jeff, as we are on the topic of legal issues and it's your own expertise field...
Is any special and formal authorization from the owner needed to display photos that are not your own on a website? I am thinking especially of eBay auctions pictures, which one can download in order to have a quieter and better assessment. I, for one, usually keep such photos afterwards for my own "educational" (as it were) purposes. Of course I am talking about displaying these photos on non-profit and educational sites, such as the Heuer gallery that you so skillfully crafted for OtD.
Any advice on the matter would be very helpful in my opinion.
Thanks anyway.
Fabrizio