Purina does such. As far as I can tell, it's only for their Cat Chow and not Dog Chow, I don't know why, so I suppose this only applies to cat owners. It's a simple rewards program, you amass points for buying their products and doing other various things on their site. These rewards can be redeemed for things as small as a coupon to as large as a vacuum cleaner. As with all rewards programs that I take part in, when there are large rewards that are actually quite valuable, I wait and build up the points to do so. This is my plan here, to get the vacuum which is worth several hundred dollars and then sell the vacuum, so I actually make money. Most small rewards are not worth it, the points needed to redeem it is actually much more than if you were just to buy it.
So if you have a cat, I suggest signing up for Purina Pet Perks.
And check out my post on Fresh Step Paw Points for rewards on cat litter!