I just bought something there and the woman working there said give them your email every time you purchase something...customers who give the email each time seem to be telling her that they are recieving coupons vs. those who say I'm already on the mailing list. I don't shop there much, so I don't know if its true.
I don't normally order things from pottery barn online, but I ordered something recently and they sent me a $10 gift card coupon good on a purchase of $10 or more. It can't be used in kids, but maybe kids is doing the same...