Remember those intimately personalized Gap billboards in Minority Report? It just occured to me that many of the pieces are already in place. We have people implanting RFID chips under their skin (the rest of us will be carrying RFID passports). A couple of years ago Microsoft has been awarded a patent for using human skin as a power conduit and data bus (read the news). Then, Korean researchers developed a chip that allows you to listen to music "using your forearm as the transmission wire for the audio signals" (CNet). See? Here is your technology for personally targeted audio ads.