I found comicvine’s list of Doctor Doom appearances to be very useful, especially since they show the covers, which is a handy visual guide for when I’m hunting down certain issues in print. While I’ll probably never have everything Doctor Doom has appeared in, it’s nice to have goals. Actually, I use comicvine’s character appearance pages a lot.
If you do torrents, there’s also a couple of Doctor Doom in chronological order downloads floating around Demonoid. What was really nice about those is that everything was nicely sorted in folders by chronological order and by story arc. It doesn’t quite have everything, though. It’s pretty handy for deciding if I really need particular issues with Doom in it, like do I really need something where he only appears in one panel in the background?
As for that anon, lol they tried. :’)