I love the new reusable grocery bags they have at Wegmans. At only $1 a bag we were able to get three for each of our cars so we always have them when we stop for groceries. (that is three for my bug and three for Aaron's truck... oooh.. maybe I should get some for Aaron's scooter)
When Tina and I were in San Francisco we each bought these reusable ChicoBags. They aren't as cute as the ones featured on delight.com (found via NotMartha), but I like how small they roll up. The ChicoBags are perfect for shopping trips... I just need to get better at remembering to carry them with me.