Image taken from here.
Unfortunately I don't know so much about print comics myself, but I'd like to start off with a plug for Rainbow Masks. It's not a comic, but a new blog started by a friend of mine in the vein of Gail Simone's Women In Refrigerators. EDITED: I should probably add that the theme of both WIR and "Who cares...?" below is violent deaths, so it doesn't make for nice reading. Not for the squeamish - you're pretty safe with Rainbow Masks, though.
Following those links will probably explain better than I can, but basically it's a list of gay superheroes and an account of their treatment in comics. It follows on from Perry Moore's Who cares about the death of a gay superhero anyway? which was apparently not as accurate as it could have been. I don't know enough about that to really comment, but I think the idea's really interesting, so check it out.
It's a big project so if anyone can help him out or correct him just leave a comment!