Rap Genius has recently received quite the hefty investment from venture capitalist firm, Adreessen Horowitz. The financial backing comes in the form of $15 million awarded to the crowd-sourced hip-hop lyrics site as the investing company sees truly creative and innovative promise from the folks at Rap Genius.

Given that Rap Genius is a web site where people explain rap lyrics, and given that my partner Ben [Horowitz] is a noted rap fanatic, your first reaction might be, “That Horowitz guy has completely lost his mind.” I, on the other hand, find rap every bit as comprehensible as ancient Mesopotamian… Let me explain why we’ve invested in Rap Genius. First, there is the undeniable, irrepressable phenomenon that Rap Genius already is – the definitive online community of rap aficionados; one of the fastest growing web sites in Y Combinator’s history; a thriving ecosystem of ideas, artists, and fans.

It turns out that Rap Genius has a much bigger idea and a much broader mission than that. Which is: Generalize out to many other categories of text… annotate the world… be the knowledge about the knowledge… create the Internet Talmud…

There’s music in other genres and other languages, but what other categories? Poetry, literature, the Bible, political speeches, legal texts, science papers. And those are just the start. We think the community will continue to expand beyond rap into all culture. The potential of this company is large.

Finally, there’s the other reason – maybe even the real reason – why I’m so fired up about this idea and this investment. 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.