Bought a few Sin City novels a couple of days ago, was rather happy to see a number of Hellboy references in there...
In A Dame To Kill For, some drunk in a bar is wearing a Hellboy tshirt and further on in the book, a prostitute in old town has a nice Hellboy keyring.
Theres also the film Dogma, in which one of the roller-blading Stygian triplets is wearing a Hellboy tshirt.
Anyone else spotted any references in other media? And how awesome would Frank Miller's take on Hellboy/BPRD be?