A Swedish app called Recognizr lets you point your smartphone camera at someone and retrieve their online profiles via face recognition. You don't even have to know the person, unlike with competing apps.
The technology isn't quite stalker friendly yet; only people who have opted in can be recognized, and the code only runs on Android smartphones. But we figure it's only a matter of time before someone writes a no-holds-barred, recognize-anyone version for the massive iPhone platform, and makes a bundle in the process. After that happens, there will be no need to make up fake phone numbers for creeps in bars — the creeps will already have your contact info. Progress.