June 30 is Social Media Day, an annual celebration from Mashable, a popular tech news site. Today Mashable announced a contest that’s highly relevant to community news outlets that use social media…

“This year we want to dig deep and find out exactly how social media has affected your community,” writes Nina Frazier of Mashable. “Whether it’s using Twitter to break down barriers to your local government or creating new ways to communicate with your neighbors, let us know. We want to hear from you. How has social media impacted your local community?”

If you’ve got a good story to tell, write it up as a comment to Mashable’s contest announcement post. Mashable will select five of the most inspired answers as winners. Each will receive a 4G Motorola Droid Razr Maxx (a $300 value, you’ll need to get your own Verizon plan for it) as well as recognition from Mashable.

Mashable is hosting Social Media Day meetups in nearly 500 cities around the world. You can also host your own—and gain visibility for it by using the hashtag #SMday. Organizer tools available from the Social Media Day webpage.

(Disclosure: I already entered this contest to describe how YouTube videos and other social media turned outrage in Oakland, California over the 2009 police shooting of Oscar Grant into a powerful local movement—and also sparked the founding of OaklandLocal, a community news site and platform I co-founded. But if you come up with a better story, more power to you!)

The News for Digital Journalists blog is made possible by a grant to USC Annenberg from the John S. and James L. Knight Foundation.