Peering into the dark side of online media, U.S. Sen. Al Franken wants the Justice Department to study the rapid proliferation of "geotags," data about a person's location derived from photos and videos made with smartphones and other mobile devices equipped with GPS or other location-fixing technologies.

The Minnesota Democrat worries what stalkers could do with the information. "While embedded geotags may be desirable features for many consumers, I am troubled by how easily this information can be made public without the user's knowledge," he wrote in a letter Monday to Attorney General Eric Holder. Franken continues: "(A) stalking victim who posts a photo or message to friends online may unwittingly broadcast his or her exact location to a stalker or anyone else who cares enough to look." What does he want Holder to do? Collect the "necessary" data and make policy recommendations to Congress.