Here's something I can not live without. My Food Notebook.
I keep this handy little Laura Ashley book with me always. I write down grocery lists, things I might need to pick up, flavor combinations I want to try, and recipe ideas. I also write down what's on sale, so I won't forget to pick it up when I go to the market.
With all of the many things I have going on, this keeps all of my food related ideas in one place. That way, when I prepare my grocery list for the week, my notes are together.