LOS ANGELES (AP) — We're digging deep in the vaults this week, going all the way back to 1999 to look at movies with viral buzz.

These are films that cultivated a mystique about them, an urgent, must-see aura, based on unorthodox marketing methods. Maybe it's a creepy website. Maybe it's a few delicious details trickled out to a specific fan base. Maybe social media propels the buzz. Or maybe just a great title gets people talking.

With "Paranormal Activity 2" opening this week (see review below), here are five movies that have benefited from that intangible but irresistible viral buzz:

• "Paranormal Activity" (2009): Sure, the phenomenon existed long before this horror movie came out last year, but this is a film that really capitalised on the power of Twitter and cheap online promotion, that rode a wave of excited, instantaneous word-of-mouth. The movie itself had a pretty simple concept: It created the sensation that we were watching actual home video, shot in a bedroom overnight to capture whatever demon was haunting its young, female hero. It only cost about $10,000 to make, opened in just a few theaters at first to generate even more curiosity, and went to gross nearly $108 million. Hence, a year later, we have a sequel.

l "The Blair Witch Project" (1999): The mother of them all. Just saying the words "Blair Witch" serves as an instant shorthand: People know exactly what you mean. The gimmick, in case you've forgotten, is that we were supposedly watching the real, final footage of a trio of friends who entered the woods to make a documentary about the legendary Blair Witch. They shot every moment and every movement they made — including their last. A debut at the Sundance Film Festival kicked off the talk. Unknown actors played the three characters, furthering the possibility that this was all authentic. A website pushed the idea that this was legitimate, adding to the eeriness. The movie made nearly $141 million; a year later, though, the secret was out and the hype was gone, and the sequel, "Book of Shadows: Blair Witch 2", only made about $26 million.

l "Cloverfield" (2008): Excitement for this thriller built in increments, but it was undeniable. The trailer, with its image of the Statue of Liberty's severed head bouncing down a Manhattan street, created huge buzz online and at Comic-Con. The title gave away nothing — it's just the name of a street near producer J.J. Abrams' Los Angeles office, a code word the filmmakers used to keep the project under wraps — but it stuck, adding even more mystery. And the premise was tailor-made for the YouTube generation: a monster attack on New York City as seen entirely from the perspective of a partygoer's hand-held video camera. Plus, director Matt Reeves' film happened to be a lot of fun, and it went on to make a respectable $80 million.

• "Aqua Teen Hunger Force Colon Movie Film for Theaters" (2007): Most people probably hadn't heard of the animated series "Aqua Teen Hunger Force", which airs on Cartoon Network's late-night Adult Swim line-up, and provided the basis for this movie. It follows the intentionally Dadaist adventures of a wad of hamburger meat, a milkshake and a container of fries who share a rundown New Jersey tract house. The promotion included blinking, Lite-Brite-style renderings of alien characters known as the Mooninites, which were placed in major cities nationwide. In most places, no one thought twice about them. In Boston, they were viewed as a potential terrorist threat, forcing the closure of bridges and roadways. It might not have helped at the box office, where the movie made only about $5.5 million. But it got folks talking.

l"Snakes on a Plane" (2006): It's exactly what you think: a thriller about snakes . . . on a plane. Just the title alone promised a campy good time, a throwback to star-studded disaster action pictures like the 1970s "Airport" movies. Adding to the fun, fans who saw the movie early urged the filmmakers to keep a crucial Samuel L. Jackson line in the script with a particularly colourful 12-letter word — and they got their wish. It's a hugely crowd-pleasing moment, and watching the movie with a giant crowd was the best way to do it. But people talked about the movie more than they actually went to see it. "Snakes on a Plane" opened at No. 1 with nearly $14 million but only went on to make $34 million — which is a shame, because this was one hell of a ride.