Bike concept turns into cart
Green types that like to ride their bike to buy groceries rather than having to drive to the store, but worry that their bike will get stolen will get a kick out of the Urban Folding Bicycle concept. The concept was designed by Hyuk-Jae Chang and won a bronze prize at the IDEA Design Awards 2010.
The basic concept is a normalish looking bike that you can ride around town with a chain and disc brakes. Once you get to the store rather than chain your bike to a post or bike rack, you simply fold it down into your own shopping card.
The cart has a push handle and a pair of baskets for your purchases. Once back outside you unfold the bike again and ride away. The only downside I see is that the baskets are a bit small. You won't be buying many groceries at once.