Bump Technologies, the startup that first grabbed attention by allowing users to “bump” their phones together and share contact information, just raised $16 million in a second round of funding.

The company has an impressive lineup of investors — Andreessen Horowitz, the firm co-founded by Netscape creator Marc Andreessen, led the current round. Past backers Sequoia Capital, Ram Shiram’s Sherpalo Ventures, and Ron Conway’s SV Angels also participated. Andreessen is joining the Bump board.

Although I still think of Bump as a contact-sharing company, chief executive David Lieb and co-founder Jake Mintz told me that I’m a little behind the times. They said that after observing that Bump was mostly used on nights and weekends in social contexts, they added other kinds of sharing like music and photos. Now photos are the most-shared item on Bump, with 20 photos shared every second.

The app (which is available for iOS and Android devices) now has 25 million users, with 1 million users added in the last two weeks alone. The app is free, and Lieb said the company is focused on improving the product for now, then adding features to make money later on.

As for future plans, Lieb said Bump is looking beyond person-to-person interactions. It’s too early to talk about new features, he said, but one of the most-requested additions has come from musicians who want to find ways to share music and other media with their fans.

Bump was incubated by Y Combinator. Don’t confuse it with another company called Bump, which has created social networking tools around license plates.