I always have a list of stuff to do, though I never look at it untill I get a call like 'did you forget about x apointment'.
I do shop with a list and I do almost always check it before I leave the store, not when I first get in, that would make to much sense. Oh no, it is the last thing I do before checking out, or what really annoys the checkout people is when I do it while checking out and then have to send my poor hubby rushing off to find something before the cart is empty. Of coruse the list doesn't help when I forgot to put stuff on the list.
