Almost never. I love PB and believe me, I've looked and looked all over the Internet for free shipping, codes and coupons that the "general public" can use for PB. They just don't offer them.
The only coupon codes I've ever had from PB were personalized (could not be shared), and I've gotten exactly two of them in the past several years. One was when we moved -- we got a "welcome" letter in the mail, based on our post office change of address, with a 10% off code. At the end of that same year, because we had bought a ton of furniture for our new house from PB, we got a 20% code good for 6 weeks, encouraging us to buy more. That one was so rare that when I used it for a phone order, the rep said "wow, I've never heard of a 20% off code!"
If you open a PB credit card, they will give you a 5% "rebate" (in the form of a PB gift certificate) on everything you buy with it within the first 30 days. After the first 30 days they will occasionally have offers where if you spend so much in a certain length of time, they'll give you a small gift certificate. You can apply online from the PB web site (look at the bottom for a link to the credit card page).
Mary
MouseSavers.com