Just about every movie gets marketed online these days. It used to be the studios stumping up for a basic official site, then interactive content crept in, and things have evolved even further in this techno-savvy era.

Now, the likes of Twitter and Facebook, though their final impact has yet to be accurately measured, are being plumbed for their benefits.

Paramount set about capitalising on the word-of-mouth buzz by ramping up the film slowly.

In September, the movie was screened simultaneously in seven cities across the US as part of Fantastic Fest. That was quickly followed by a college town tour.

Midnight screenings began to sell out - as the old saying goes, an impossible ticket is a hot ticket - and the legend of the film spread. Paramount cannily put webcams in several cinemas so audiences could record their shellshocked impressions.

And the smartest move? Using a piece of web technology usually associated with smaller music acts, where fans can "demand" a gig - or in this case, a screening -  take place in their town.

The studio ramped up the tension by announcing that should 1 million "demands" be registered, the film would be released wide across the US.

There are differing opinions on whether it would actually have gone through with a muted release should the counter have fallen short - cinema owners have reported that the plans were in place for a wider October schedule before the demands began coming in.

If it's not quite as grassroots as truly public-generated movements (some have sneered that it's "astroturf" - an entirely invented strategy with little concern with how the Demand experiment turned out), it does seem to have worked.

"It's very rewarding to see the fans embracing the movie. This is totally a fan driven movie, because if it wasn't for the fans, we wouldn't be talking right now.

"This movie was launched by Paramount in a way that really allows people to decide whether or not they want the movie to be released and where.

"So if it weren't for them demanding the movie and saying, 'We want it to play in our home town' and if it weren't for the fans spreading the good word online in forums or on Twitter, the movie probably wouldn't have gotten anywhere," says Peli.

Finally, it was time for Paranormal Activity to occur on a wider scale…

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