For my daughters 6th birthday, we had a "Shop till you Drop" party.  For the invitations, I printed invitations on the  computer, and sent them in very small gift bags, to look like a shopping bag.  We took all of the children to the Dollar Tree dollar store, and told them they could each shop for 6 items- they could pick out whatever they liked! They had so much fun "shopping" for whatever they wanted.  We then came home and had cake and ice cream.  The cake was a "shopping bag."  I used a 9 x 13" rectangular cake, iced it pink, and used a shopping bag handle, inserted at the top. (You could also use shoestring red licorice) I put some tissue paper coming out of the top of the bag, and bought a couple of trinkets, to "spill" out of the bag- I used a necklace, and a couple of shoe keyrings. The girls also decorated brown gift/shopping bags, and placed all of their purchases in the bags to take home.