This could get interesting when coupled with some powerful image recognition. Say, for example, you want to repair something on your car. Load up the repair manual, and let the overlay show you step by step what to do, e.g. a certain screw gets highlighted right were it is and the popup text tells you to now fasten this screw to this-and-that torque.
Wait, are you implying that augmented reality glasses are a good idea for augmented reality applications?