Change.org is a great example of a social network that harnesses — or focuses — people’s passion. So many “me too” social networking sites lack this key ingredient.

If your social network is going to take off, it will need to tap into a passion or need powerful enough to get people signed up and engaged on an ongoing basis.

This isn’t an easy feat.

Luckily enough, people are crazy-passionate about millions of things. If you can provide a venue where people can share this passion, and — even better — generate enough critical mass to give them voice and momentum, the you have a community.

That’s what Change.org does so well.