None of the grocery stores in my town have reward or membership cards but I do use a reward card at Famous Footwear and Staples.
Famous Footwear sends me a $5 coupon on any purchase at least 4 times a year and they send bigger coupons if I buy more shoes there.
Today I used 2 $5 coupons at Famous Footwear and got 12 pairs of socks for just $2.18.
My office uses a lot of ink cartridges in our printers and I take the empty ones to Staples for recycling. They used to give a $3 gift certificate on the spot for each cartridge turned in. They have recently changed their policy and now they allow 3 cartridges a day and the $3 for each one gets rolled to your quarterly reward. This is still a good deal but the reward is not as quick.