I keep a magnetic list on my fridge, too, so when I run out of something it goes on the list. It is so helpful when I am ready to go to the grocery!
I also kind of do Rachel Ray's garbage bowl, only mine is a habit learned from my Gramma, I use a grocery bag with the handles and sides turned down a bit so it will stand up on it's own and let it sit in the sink and all my garbage goes in it as I prepare/cook then I tie it up and it goes right in the trash. Very handy.
I always keep instant mashed potatoes onhand, they are good for thickening homemade mashed potatoes if you put too much milk in them.
I always clean out the fridge before I go to the grocery, it's just so much easier when I get home to put everything right into the fridge. Same for the cupboards, I straighten them and get them organized so when I get home I can just fill them up.