After years of advertisers aggressively tapping every spare inch of in-store real estate, you may have assumed there wouldn't be too many more frontiers for ads in the hallowed neon halls where we buy our Cap'n Crunch. But they're much smarter than you thought.

New company Modstream wants to put in-store advertising in the hands of shoppers--not in terms of customization of user-based input, of course. It's taking the concept literally, with scrolling text displays on the handles of shopping carts, so advertisers can beam messages to selected stores wirelessly. Then shoppers can remember to pick up the latest pro-biotic yogurt brand they didn't know they needed.

Thanks, technology!