We live a few blocks from the grocery store, and often take the baby for a walk to get food for lunch or dinner. When I take the baby by myself, the problem is that it is too difficult to push a cart or carry a basket and push the stroller at the same time.
So I went to the hardware store in search of a solution and found these cheap hooks for about $1 each.
We keep the metal hooks in the bottom of the basket, and whenever I'm at the store, I pop them on either side of the basket and attach the basket to the stroller.
My wife, who initially shunned my idea (and often does until she tries them), now asks for me to get the hooks out even if both of us go to the store together, where one of us could have held the basket. Why not? Its much easier!
When walking home, we usually put the food in the bottom of the stroller, underneath the baby seat. If we buy too much food, we simply hang the extra bags from the stroller with the hook, so we don't have to carry the bags on the walk home.