Zombies, hundreds of them, walked slowly down the hill toward the sunset.

They were a varied lot, shuffling along Salt Lake City's 500 South on Sunday evening: Zombie brides, zombie prom queens, zombie punk rockers, zombie toddlers riding on the shoulders of zombie dads, led by a zombie James T. Kirk and a zombie Indiana Jones.

About 500 zombies gathered to participate in the second annual Salt Lake City Zombie Walk, an event organized via the Internet just for the heck of it, to see how many people would dress up like the undead.

Apparently, a lot of people -- forming a line that stretched nearly two city blocks -- were willing to walk from Mount Olivet Cemetery (where else would zombies appear?) to Trolley Square (shopping malls being a natural location for zombies, as George A. Romero's "Dawn of the Dead" proved).

They were drawn via e-mails, MySpace and Twitter exchanges -- a prime example of how the Internet can turn a small gathering into a major event.

"If I didn't have the Internet," said Sarvas Berry, who organized the first Salt Lake City Zombie Walk last year, "I would be stuck with five of my friends hanging out and dressing like zombies."

Berry and his friends launched the Salt Lake event after hearing about gatherings of thousands of zombies in Toronto, Canada, and Sydney, Australia.

"I went to a web site and saw that Boise had one," said Berry, a professional body piercer who now works in Chicago and missed Sunday's walk. "I thought, 'If Boise can have one, why can't we?' "

Berry sent a few e-mails out to friends, who sent them to their friends, and so on. Ultimately, Berry said, nearly 300 people showed up in zombie costumes to walk from Memory Grove to The Gateway. (Berry said Gateway executives warned the zombies to stay off the mall this year or risk trespassing charges.)

While a troupe of zombies walking past Temple Square makes for an interesting visual, Berry said it doesn't have the same visceral effect of zombies walking through a residential neighborhood -- which the route of this year's walk achieved.

"In the back of people's minds, people really believe there will be a zombie apocalypse," Berry said.

Instantaneous events on the Internet, sometimes called "flash mobs," have popped up all over the world -- often far beyond the expectations of their originators.

Last month, according to The Oregonian newspaper, the comedian Dave Chappelle told a handful of waiters and baristas in Portland that he would be giving a free midnight show at Portland's downtown Pioneer Square. Text messages and Twitter posts circulated, and Chappelle was greeted by a crowd of 4,000 people.

Also last month, a single notice on the Facebook fan page for the University of Utah's alumni association -- advertising a talk with Ute basketball coach Jim Boylen -- drew hundreds of people, said Josh Paulsen, marketing analyst for the University of Utah's marketing and communications department.

One of the best uses of social-networking tools like Facebook and Twitter is to prompt one-on-one communication, as people use the technology to make friends in the real world. After Sunday's walk, a couple of zombies traded messages through Twitter to meet for pie at Village Inn.

Too bad Bill & Nada's restaurant, the old 24-hour hangout near Trolley Square, closed in 1999. The zombies would have enjoyed the brains and eggs.

Sean P. Means writes the Culture Vulture in daily blog form at blogs.sltrib.com/vulture -- where you can see photos of the Zombie Walk.