Nokia have barcode technology available for their phones, however I have researched its usage which is fairly limited. My idea would be for the likes of large brand name mobile companies to work in conjunction with large retail food outlets i.e. Wallmart(ASDA), Tesco. A bluetooth signal could run in the store which will be picked up by customers' mobiles on entering the shop. As well as showing special offers it could open the access to their database of barcodes for all of its products...