I think it's the ethos of the whole thing that is so attractive to me. As Jimmy says, the success relates to having a devoted community that cares.
It reminds me of the Margaret Mead quote "Never underestimate the power of a small and committed group of people to change the world, indeed it is the only thing that ever has". (or something like that)
My favorite quote:
I was recently on a panel with the head of USAToday.com. He said they have 300 million pageviews a month. I said that's good; we have 400 million. Then he said he had 180 people on staff. I said I have one part-time person who helps me with the servers. There's something new going on here. It's not about broadcast, it's about interaction.
That just sounds so right to me.