If you haven't ever done this, I highly recommend it.
Last summer I sat down and made a list of the grocery items that we use regularly or those that we particularly love. Then, I worked down the list and contacted the companies that made those products. Most of the time you can google the product name, find the website and then click "contact us" (usually at the bottom of the site). It's simple and takes very little time.
Most of the time I just complimented on the product. But there have been a few times when I've complained or voiced concern. I would say that about 80% of the companies that I contacted responded by mailing me a coupon. The coupons were far better than the ones in the newspaper. Many of them were for free product or for several dollars off a single item. I only had 2 companies that responded negatively and now I no longer buy those brands.
Here are just a few of the products/companies that sent awesome coupons:
Edy's ice cream
Skinny Cow Ice Cream
Try it out!