My shopping list application is the 'todo' application on my Palm PDA.. I have a semi-permanent list of items (milk, cheese, onions etc) there and I simply tick them off (as in removing a tick if there's one) at the moment I realise I'm out of, say, rice. I only rarely have time to visit shops, so when the chance comes up I simply walk in and get my PDA out. There will be a list of 'unticked' groceries there, and I don't have to remember anything.

This works very well for me. I saw the idea mentioned in a PDA magazine years ago and thought it sounded stupid. But later I found that it was brilliant.