Tiny Pictures, creator of the Radar mobile photo-sharing application, has raised $7.2 million from Draper Fisher Jurvetson and existing investor Mohr Davidow Ventures

The company had previously raised $4 million, including money from angel investors Reid Hoffman and Joi Ito.

Radar says it is the largest mobile photo-sharing site of its kind, with more than 15 million pictures per month being shared by its members. The company has been getting traction around the world, and has begun number of projects to spur that growth. On the carrier side, the company has partnered with T-Mobile Germany, Research In Motion and other large clients to get its application easily accessible on subscribers’ phones. It has also developed language-specific WAP sit.

San Francisco-based Tiny Pictures has also recently begun experimenting with its own mobile advertising service, where brands can buy ads that appear alongside people’s pictures.

To boost its public profile, the company has also invited Black Eyed Peas frontman will.i.am to join its advisory board last month. He will use Radar to promote his other projects.