The leading information channels prior to 2004 have been the then existing "Hellboy.com" website curated by one Jonell Napper, featuring a Publication List as consisting of all the various editions by their printings.
There was a "Wraithspace Comixology" website containing a sort of thorough Mignola bibliography.
And another website called "the Art of Mignola" curated by one Nick Warmack.
Plus the magazine "Comic Book Artist #23" (TwoMorrows Publications) coming with a then (mostly) complete Hell-verse bibliography.
By following it all or trying to, for Hellboy eversince 1995 and for Mignola since the 1980s, I've tried to collect and enjoy it all, with mapping out all of what would have come to be available. I don't have everything but a whole lot and I at least know of all books and editions and stuffs out there.
There's not a trick or treat I wouldn't be willing to share on here. Although as far as all the different merch or t-shirts and Convention exclusives I do draw a certain line for myself. Because there is just too much of that to keep up with. But chances are I would know of just about all of that stuff.
And I'm lazy.
But now I gotta tend to be doing my housecleaning big time. And I'm lazy, so I mope while I mop.