So far, Google has only scratched the surface of the advertising potential here. That makes sense: How many times in your life are you actually going to point your phone at an ad?Google glasses could change all that. Now the user doesn’t have to point his phone at an ad to activate the AR [augmented reality] layer — he only has to look at it. Combine that with location data and all the other rich targeting information Google has at its disposal and you’re talking about potentially the most valuable advertising medium ever invented.Imagine it: You’re walking home from work. You put on your Google Glasses to check your email and notice that the sushi place across the street, where you frequently go for takeout, is highlighted. In the window is a glowing icon that lets you know there’s a discount available. A tiny tilt of your head brings up the offer: 40% off any purchase plus free edamame. With a bit more tilting and nodding, you place your order. By the time you cross the street, it’s ready for you. Would you like to pay via Google Wallet?You nod.