Photo Tagger relies on facial recognition technology to automatically tag photos and identify faces within the million of photos uploaded on Facebook. It puts the photos into groups and suggests tags. The confirmed tags are pushed directly onto Facebook, following privacy settings, with the result an album of tagged photos.

Several algorithms work together to determine whether the photos are out of focus or have other problems, like something covering part of the face. The Face Alerts feature continually scans newly uploaded, untagged and tagged photos to notify people whenever their face is found. Think Google Alerts, but in this case the application searches for pictures of the person setting the parameters.

The technology focuses on facial characteristics that make each photo different, according to Gil Hirsch, CEO of Face.com. "Faces are not that different, but we needed to teach a machine to tackle that problem," he says.

And while Hirsch insists Face.com designed the application for consumers to monitor their online identity, the technology presents opportunities for advertisers and marketers, too. "Facial recognition technology can provide ad targeting information to marketers and advertisers, but we're not pursuing this market right now," he says.

Other marketing apps might include retail application, lead generation, and conference-related applications. Marketers could profile people based on their facial expressions.

It appears that publishers of social networks have shown interest in the technology, according to Hirsch. "We've been asked to add the tagging technology on third-party sites, but, again, we're not actively pursuing this," he says. "Generating tags in pictures of people who are not users of a social network site might prompt that person to join."

Hirsch admits facial recognition has had negative undertones, such as big brother or privacy issues. "For some people it might feel a little creepy, but we're tying to show people how it can be used to produce a fun and useful experience," he says.

Coca-Cola recently tried to use a similar technology in a marketing promotion. The Coke Zero Facial Profiler app on Facebook invited users to upload their photos to a database to match people's faces using recognition technology. The campaign aimed to emphasize that the no-calorie Coke Zero tastes just like the real thing, but some consumers were more annoyed than engaged.