> My understanding is that having a card and never using it IS actually good for your credit rating. I've been told it's a good idea, when you're a teenager, to have a credit card that you're not allowed to use, as then you get credit when you may need it later. But I don't have any evidence to support this theory, and I don't even really know where this impression originated. And, for all I know, if it were once true, it may not be anymore.

I've heard that. My aunt told me I should do it. She tried to make a point of saying that what I should NOT do is get a bazillion credit cards and max them all out, but somehow her point got muddled and the conversation ended in, "NO, do NOT tell your parents that I'm telling you max out all your credit cards that you don't even have, because that is NOT what I'm saying!" I love my family.