I saw this yesterday and felt like it needed to be passed along. (It's 17 minutes.) I know that a lot of people talk about 'tribes' now. I've seen some of the most narcissistic people I know discuss how they are leaders of tribes. Because of that, I've stayed away from my beloved Seth Godin's talks on tribe.
Not surprisingly, the actual conversation about tribes has very little to do with ego, and more to do with changing the world for the better.
If you can make the time, this talk is worth watching.