In a related story to the recent "Bottled Water" piece, I would like to point out the urgent need to follow suit with retailers like Ikea and grocery stores in several countries, such as China, Switzerland, Ireland, Austria, and cities like San Francisco and Oakland.
Ikea and some of these other stores in other countries, charge 5-10 cents per plastic bag. The usage of plastic bags has subsequently decreased by 95%. Obviously, in some cases, bags are useful and needed, but it many other cases (buying just one or two items), the bags are really not needed and are just a waste. Remember, these bags will not degrade for over 10,000 years.
Next time you are at the store, think about whether you really need a bag to carry out your merchandise to the car (or to your bike).