Viral websites. Aren’t they fascinating?
It was really Christopher Nolan’s “The Dark Knight” that revolutionized their use in a movie’s advertising campaign. I remember there was a site for just about everything in Gotham – the newspaper, the bank, the police, even the pizzeria.
Sure enough, “District 9” carved out a nice audience for itself using a similar campaign the next summer with the “Humans Only” signs on bathrooms and benches and such. And Nolan’s own “Inception” is doing the same now.
I slap myself for not getting more involved with “The Dark Knight” viral sites. They really did reward the people who stuck with them. I remembered hearing that the people who put their names in had been sent free advanced screening passes to see the movie in IMAX. Of course, only then did I scour the websites looking for a way to get my hands on the passes. It was to no avail; I even called the number on the pizza site.
And for the record, my self-imposed moratorium on intake of “Inception” has kept me from joining their viral site.
Marshall and the Movies 
I got a bunch of elect Harvey Dent stuff that kept me involved. No passes though.
I personally never got into them to be honest. The only one that caught my attention was the I Love Bees viral for the Halo 2 video game several years ago. It looks like WB might be gearing up for a viral campaign for Batman 3 (http://www.cinematical.com/2010/07/13/is-warner-bros-beginning-its-batman-3-viral-marketing/)
I saw that same article today – I’m game.