Newark's Mayor Cory Booker shares President Obama's deep understanding of the power of digital media as a means for community organizing. As of yesterday, Mayor Booker has 833,779 Twitter followers, and 14,768 Facebook supporters.

According to the US Census Bureau the Population of Newark is 281,402 (2006 estimate) which means that Booker has more than 3 times the population of Newark following him on Twitter and the equivalent of 5% of the population of Newark as Facebook supporters.

When he post to his Facebook page, you can see by the volume of "comments" and "likes" that his Facebook supporters are actually engaged in conversation with him. So, what is he doing that fosters engagement?

Authenticity and humor are powerful tools when it comes to getting your audience to engage with you, and Mayor Booker understands this. He, jokingly, used Facebook and Twitter as a platform to challenge Obama. He asked his Facebook supporters and Twitter followers if they thought his jump shot is better than Obama's.

He uses Twitter to warn the citizen's of Newark should they litter, they are in danger of getting pulled over by him.

And he shares words of wisdom that inspire him.

So Mayor Booker--I am not sure if you jump shot is better than Obama's, and I promise you that I won't litter in Newark-or anywhere else for that matter. I thank you for your words of wisdom and I applaud you for your understanding of social media engagement.

This post brings together two chapters of the recently published report Social by Social: a practical guide to using new technologies to deliver social impact. Commissioned by NESTA, it provides a collection of tools to engage communities, offer services, scale up activities and sustain public service projects both from inside and outside government.