Friendster versus Orkut
I saw this traffic ranking chart that shows how quickly Friendster caught on, and I was impressed with it.
Until I saw this one:
That meteoric spike of traffic is Google’s foray into the social network space with a little website called Orkut. Apparently, Google wanted to acquire Friendster at first, but was turned down, so they started their own. They launched the site by sending out 12,000 invitations, then waited for those people to invite others. Orkut is an interesting social experiment because you can only join by invitation.