Today in my Gold Box:

"I'm sorry, but we've just run out of this item. Our Gold Box deals are so good, we sometimes can't keep up!"

Sounds like another clever way to have you check out this box every time you see it. I suspect you don't always get to see it on purpose (you're supposed to get one every 24 hours, but it seems to behave more erratically).

When you do see it, and the items are still in stock, you want to get your wallet out! I mean, do I really want to "pass forever" this offer? That's really great copy that makes you ponder the item on sale. "Do I need it? I mean, I might want to own this in the future, or find it useful. OK, maybe not for me, but do I know someone who might want this?"

For one, I suspect these sales are at least partly backed by vendors, so Amazon doesn't have to eat the coupon cost on their margin. It's also a great way to expose products from all departments. You might never go to their Tools & Hardware store, but everyone loves a good deal, and I'd bet this Gold Box gets a lot of clicks.