Any discussion of viral marketing of this year's crop of popcorn flicks has to begin with the mack daddy, "Dark Knight." I could write a whole article just on this movie because it's employed what may be the most expansive, complex, ambitious and audacious use of new media to market a film since "The Blair Witch Project."

There's a dichotomy built in to that comparison though. On the one side you have a sequel in a lucrative franchise with a huge following and built-in fan base; on the other, you have an original and completely unknown story. One is a mega-budget studio release; the other, an indie film produced on a shoestring. And obviously one of them had 10 years of experience and technology developments to work off. But at the core the two approaches are similar: create intrigue and invite moviegoers into the film's universe.

This sort of "experiential marketing," takes a role-playing concept, not unlike video games like "Grand Theft Auto," and applies it to a film. The folks marketing "Dark Knight" know what they're doing and are clearly creative, clever and well funded. At my last count there are at least 36 unique websites directly tied to "Dark Knight's" viral marketing campaign -- which is kind of insane in and of itself. But then so is the Joker. And Two Face. And Bruce Wayne…

We have Harvey Dent's campaign website and a blogger based in the Gotham City D.A.'s office; various citizen's action groups, lawyers and the G.C.P.D site. You can tune in to Gotham Cable News or peruse the Maiden Avenue Report or the Ha Ha Ha Times. There are websites for the local Gotham church, bank, travel agency and taxi service, among others. And these sites all contribute to elaborate nationwide hunts for more clues, which are in turn seeded on fan's blogs and other sites. The scope is staggering, and each offers tantalizing clues to what may happen in the film.

There are two potential downsides to this sort of campaign, however. First is that it's labor intensive (for fans, not just the marketing team) without much of a payoff. As rabid a fan base as Batman has, not many people have the kind of time you need to invest in a complicated scavenger hunt. And when all you "win" is a shadowy photo, which may or may not be the Two Face character from the movie, you are defeating one of your own purposes. The goal is to allow fans to fully embrace the film's world in ways that encourage them into the box office. But you have to simultaneously keep fans at arm's length so as not to reveal too much, because giving away the candy store will make the movie experience less sweet. It's a fine line to tread.

Nevertheless, I don't think the producers of "Dark Knight" will have much to worry about on opening weekend.