Amazing that a term once reserved for the lowest rung of the social ladder, a hater’s word, has had its teeth pulled like this; I guess it was about the same time the real geeks started taking over the planet. Now everyone’s a geek of some strain, and the OED has a special mention for the new usage:
a person with an eccentric devotion to a particular interest : a computer geek.
If you have a special enthusiasm for a subject, something that isn’t shared by everyone else, or one that goes to extremes others dare not (everyone loves music, but is everyone a music geek?), you get tagged. If you don’t have an interest worth being tagged for, what kind of sad, uninteresting motherfucker are you? Go get a hobby.