I was a Friendster once. Technically, I still am. One of my housemates urged me to sign up sometime in 2004. He was trying to explain the concept to me, and I must admit that at the time I had a bit of difficulty grasping it. It was something about having friends and being able to see friends of friends. It sounded strangely similar to the practice of collecting baseball cards.
I have had a geek-fascination with the Baha'i calendar (also know as the Badi calendar) ever since rediscovering the Baha'i Faith last summer.