Untraceable
An example of Web 2.0: D
A teenager perhaps has had his part of forgettable things in his life, and turns into a troubled and a psycho serial killer.
His ways of killing are a little different. Logically, he doesn't kill his victims; he just sets things up and lets them die on their own.
So our killer in this movie, has a website (www.killwithme.com) hosted which stream lines live video of the victim, in distress, generally stuck in a helpless situation, begging for mercy. Though, our killer here does only the part of setting up the kill.

The site programmed in such a way that if any user registers a view to the website, the victim suffering increases in severity, by some system the killer set up. So more people visit the website, the faster the victim dies. I am guessing, Perhaps PHP, AJAX and a CNC: D. I don't know. They didn't mention the technology in the movie. Ha ha
[Spoiler](Sort of)
Let me give you an example from the movie, the victim is tied and has some text engraved on his chest. So he essentially bleeds. Beyond which, if more people visit the website, the strings tighten or something, so basically the victim bleeds more and finally when the number of clicks on the site starts to increase astronomically and equally fast too. The victim dies.
[/spoiler]
Visit the kill with me website.
This Killer chap in the movie just keeps picking one victim after the other, and keeps getting creative in his ways to kill, now its up to the FBI to figure out his whereabouts, his motives, why he chose those victims and of course him.
He just sets it all up and in a way, the people who visit the website, which is almost everyone, are acting as accomplice to the murders.
Its just a chase and finding the killer.
It’s not a great movie but yeah it’s a decent movie like it because of its concept, totally web 2.0 ha ha
A one time watch.
Now about the website kill with me. A clever website for publicity of the movie. The website gives offers you an option of joining the Federal agents to solve cyber crime, a small game made up of 4 puzzles are given, simple puzzles and then one hack based on the clues given to you. Simple puzzles, good entertainment, very good publicity.
Also Read: What is Web 2.0

Forever by Chris Brown