One of the better Chrome extensions I’ve used in the past year is Honey.
Honey lets shoppers both access and contribute to a database of crowdsourced coupon codes.
When you’ve populated your shopping cart and are ready to check out Honey will inject any of a number of current coupon codes into the cart to get you a discount.
Other benefits include gamification – Honey will let you refer friends and earn points to attain Honey Gold status. With this you can earn cash back when you shop. It’s truly the easiest way to apply coupon codes without searching on sketchy deals sites.
Recently added is the ability to search for the best priced seller on the Amazon marketplace – a site, like eBay which doesn’t really put out coupon codes.