I’ve had most (but not all!) of the old covers being posted here, sitting on a hard disk for years. Since the photobucket links will probably eventually die and leave these pages looking rather bare, I have uploaded about 4 GB (so far) to my site. Many of them are the same as posted above, but at a higher resolution.
I’m still generating the pages to host them so not all of them are accessible yet but they will be soon.
http://thestarwarstrilogy.com/starwars/page/Star-Wars-Cover-Art-Archive
http://thestarwarstrilogy.com/starwars/page/The-Empire-Strikes-Back-Cover-Art-Archive
http://thestarwarstrilogy.com/starwars/page/Return-of-the-Jedi-Cover-Art-Archive
… more to come