So during the day I keep a tote bag on the kitchen table (where I pass by throughout the day) and fill it with anything that I can accomplish in the car...go through mail, write my grocery list, work on a project, send cards, magazines I want to read, etc. I also throw in a couple of books or a movie for whatever kids I have with me. Then, when it's time to for pick-up, I just grab the tote bag and go.
(Yesterday I saw a woman with a dust rag attacking her dashboard during pick-up! Might have to add cleaning supplies to my bag!)