This is one of the creepier articles I've read recently.
It's always fascinating, the things people will volunteer for. Reminds me of a Yakov Smirnoff routine: in Soviet Russia, you sell out your neighbors. In America, you sell to your neighbors! What a country!
I guess it's not much different than becoming an Avon or Amway or Popular Club Plan salesperson - you've gotta prey on your nearest and dearest, get 'em roped in just as tight as you are...except with this whole voluntary-viral-marketing thing, you don't even get paid. The "agents" are literally doing it just for the pleasure they take in getting one over on the people they're marketing to - the subterfuge, and the insider cool, are the reward.
People are fucked up.
And check out the anecdote, near the end, of a guy who posted a classified ad saying nothing more than "Join Me" with a phone number. Good thing he decided to make the respondents do good deeds, and didn't just start passing out suitcase nukes and anthrax vials, huh?
More material for the next book...