Sequoia-backed Bump Technologies Inc. is closing in on 10 million downloads for its nifty contact and data-sharing app. With iPhone and iPod Touch sales estimated to be around 80 million, co-founder Jake Mintz says this means the company’s apps are on more than 10 percent of Apple’s phones.

The company launched last year with a simple, yet provocative demo. The app let you literally bump two phones together and pass contact information like phone numbers, names and e-mail addresses between them (see the video below).

But it was a feature that was easy to duplicate, and larger companies like LinkedIn later built their own variations of it for contact-sharing. To overcome the risk of becoming a feature of someone else’s product, Bump opened up and became a platform by launching an application programming interface (API). It’s a strategy we’ve seen time and time again with companies like Twitter and Foursquare, when a first-mover comes upon a useful, but easily commoditized concept. Several apps that let users share gift card codes, notes and payments have already been built on the API.

The hope is that Bump can find a business model by providing its core technology to other companies to power all kinds of physical data sharing, whether it’s trading virtual coins in a game, contact information on a business card or even payments. There are a number of interesting applications in these areas that Bump will launch during the next month or two. It’s also eyeing possibilities, particularly in gaming, on the iPad. (Yes, you can bump an iPhone to iPad or an iPad to an iPad.)

The company, which grew out of startup incubator Y Combinator, is still ironing out its business model. The most obvious path would be to license its technology and earn a revenue share or flat fee, but Mintz says the company wants to avoid using a licensing-only model. Right now, most developers that use Bump’s API can do it for free, unless their usage weighs heavily on the company’s technical infrastructure or they’re earning significant revenues off Bump’s technology.

Intuitively, it might seem that Bump is best used as an alternative to swapping business cards. But it turns out that the company’s traffic hits a peak on weekends, suggesting that it’s more of a casual or social app. The company recently launched a Facebook integration that lets users friend each other on the spot to take advantage of that. A Twitter integration that lets you follow a person will come shortly.

Bump is backed with about $4 million in funding from Sequoia Capital, Ram Shriram, Ron Conway and Y Combinator.