ah, I dunno.. something doesn't make sense.. the revenue that comes in from toys, TV, movies, etc., should have helped them out a lot by now.. as mentioned, there's always late-night TV/cable.. and ads in comix-culture magazines only reach so many of the 'unconverted'.. where are the ads in People, newsweek, sports magazines, hell, even Sci-Fi/movie magazines?
Well, as I understand it, it comes down to how the huge companies are broken down into their own departments with their own budgets. DC get a cut of DVD sales and stuff, but it's mainly done by WB animation, who licence the Justice League brand, etc. The animation dept can afford to advertise in mainstream magazines and maybe on TV, but their money is handled totally differently to DC (and they probably bring in a lot more profit). That's why you will see adverts for
JLU,
Ultimate Avengers and big screen adaptations of comic properties in more places, but not for the comics themselves. The comic companies simply can't afford it, and can only hope that the better-promoted films etc from their properties get people to check out the comics (or more likely, tpb's).