Over 24,000 used items offered at Amazon’s Used websites (aka, “Amazon Warehouse Deals”) are participating in an Earth Day promotion that automatically gets you 20% off their current prices. Only select items are eligible, and only those that Amazon itself (in this case, Warehouse Deals itself) is the seller. Things offered by 3rd-party sellers are not eligible. No coupon code needed, eligible items are discounted automatically and they show a 20% off marker when you look at the individual listings. Since this is an Earth Day promotion, it should end after Earth Day or so.