RapGenius has been a little hesitant to admit it’s a tech startup. First and foremost, the company is a community of rap lovers. Also, Bible lovers. The Brooklyn-based lyrics annotation site had raised a small round of funding last year from from New York investors including Lerer Ventures, but kept quiet about it.

It was more important to get the word out about their beefs with The New York Times and Das Racist, or their friendships with Nas and RZA.

Today they’ve come clean about the other side of their business, thanks to a big round from Andreessen Horowitz. The firm has invested $15 million. Unsurprisingly, rap-obsessed partner Ben Horowitz will join the company’s board.

In an annotated post on RapGenius’ site, Marc Andreessen, the father of the Web browser, notes one really interesting fact:

Only a handful of people know that the big missing feature from the web browser – the feature that was supposed to be in from the start but didn’t make it – is the ability to annotate any page on the Internet with commentary and additional information.

By annotating the Web, RapGenius does what Andreessen always wished he’d been able to build into the initial Web browser. RapGenius’s technology has already expanded beyond rap lyrics to annotated poetryliterature, the Biblepolitical speecheslegal texts, and science papers.

As I wrote in August, RapGenius was garnering half a million pageviews in a single day. Rappers like Nas, RZA, Kendrick Lamar, Big KRIT and 2Chainz joined to explain their own lyrics to fans. A rapper named Monster Mike got the RapGenius logo tattooed on his neck.

The company will use the cash to “trick out the experience” on the site and build a mobile app. Oh, and, according to co-founder Mahbod Moghadam, “We’re gonna buy a ton of companies.”

[Disclosure: Lerer Ventures and Marc Andreessen are investors in PandoDaily.]