A startup created to help local leaders rally citizens has mobilized quite a bit of support for its own cause.

NationBuilder, a community organizing platform for local politicians, non-profits, and causes, has bagged $6.25 million in a new funding round led by the esteemed venture capital firm Andreessen Horowitz. Andreessen Horowitz partner Ben Horowitz and round participant Sean Parker (of Napster and The Social Network fame) are joining the startup’s board of directors.

Founded in November 2009 and launched roughly one year ago, NationBuilder offers community leaders an all-in-one platform to easily establish a web presence with social hooks, run campaigns or causes, raise funds, and manage volunteer initiatives. The do-it-yourself system, which starts at $19 per month, is said to be used by more than 1,800 leaders who’ve altogether amassed more than 2 million supporters across their 500 “nations” (read: campaigns).

Isn’t this just a dressed-up WordPress copycat for non-profits and small-town politicians, you ask? In many ways, yes. But where NationBuilder excels is in delivering sophisticated features finely tuned to the exact needs of grassroots community organizers. The site, for instance, helps leaders maintain a supporter database that automatically appends public data users have shared on Facebook or Twitter (profile picture, bio, contact information etc.) for an up close and personal look at their cheerleaders.

And, according to CEO Jim Gilliam and President Joe Green, NationBuilder actually works in getting local politicians elected. Alex Torpey, for instance, was elected Village President of South Orange in May 2011. The young mayor ran and managed his campaign entirely using NationBuilder.

“NationBuilder empowers you to find who to talk to and gives you a bunch of different ways … to run a strategic and deliberate operation as a local guy running a campaign on a few thousand dollars,” Green said. “For us, the campaign office is the website,” Gilliam added.

NationBuilder is, of course, a for-charge product, which means the startup is earning revenue with each new customer — making it an especially attractive business from an investor perspective — and some of the extras such as email and text messaging to supporters come with additional fees.

NationBuilder is based in Los Angeles. The young company previously raised $500,000 in seed funding from a handful of Angels, including Facebook co-founder Chris Hughes.

Photo credit: theqspeaks/Flickr