Online supermarket Peapod is bringing its foodstuffs to Chicago's "L" transit system, with a new ad campaign that allows commuters to do their grocery shopping from directly within the city's train stations. Last week, the company plastered Chicago's State and Lake Station Tunnel with a "virtual grocery store" ad — posters of grocery shelves stocked with popular household items and food products. People travelling through the station can scan an accompanying QR code to download the free PeapodMobile app, which will allow them to scan barcodes listed on the products displayed in the ad. With the app, iPhone and Android users can place orders, manage their shopping lists, and schedule deliveries as they wait for the next train.