They are using a site called couponchief.com to locate these codes. It is a database of coupon codes that are uploaded by members. They have a ton of stores listed and multiple coupon codes for each store. Ta-Da!
I love that they even have amazon.com promo codes and codes to other online stores that you just can't find anywhere else (literally everything from Victoria's Secret to Enterprise Rent-A-Car and all stores in between!). I refuse to pay for codes on ebay when there are great services like Coupon Chief out there.
It is a very user friendly website too. Everything is organized into category and you can also search by store name. They take all the guesswork out of saving. I have tried other coupon code sites whose codes always seem to be expired or invalid, and that is just not the case here. They use a peer-reviewed rating system to determine the success rate of the coupon and even allow you to read the reviews from others' successes to see how visitors used a coupon to benefit them most so maybe you can find an extra deal or 2 along the way. I always check Coupon Chief whenever I am making an online purchase. It is the best way to ensure that I am not missing out on any deals or bargains.
Coupons 4 Causes. I love this! When you login to Coupon Chief, you can select a charity that you want them to donate to, and if you make your purchase using one of their coupon codes, they will donate up to 20% of your purchase to the charity you choose!