You obviously need an application with a database of all the ingredients for a given set of meals, which ties into a calendaring application, so you can just select items for each meal of the week, then sync up the grocery list to your palm device through a custom conduit. Bonus points for UPC scanning and pantry inventory control. Extra bonus points for dimensionality data, so you can definitely assert that the freezer won't overflow when you get the stuff home.

There's a terrible, terribly nerdy pun about compiling the week's menu in here, but i'll omit it.

(And, for the record, my fridge is empty, save one egg and some condiments. My freezer is full, but alcohol doesn't count for much nutritionally.)