Neither--I put them in line 1, contributions. The reasoning behind that is that people are basically choosing to give you a donation by doing their shopping in certain places. And the donation doesn't usually come from the individuals, it is actually from the grocery store or restaurant.
I definitely don't think any of that stuff qualifies as a special event (despite what I try to make my 3 year old think when we go grocery shopping!). There's no real harm in putting it in line 8, except that you'll have to find some generic explanation covering all those "shop and earn" programs to fit on that tiny line they give you, and it will make filling out your schedule A a little more complex.
I am working on our IRS 990-EZ form and there is one income heading that I am having trouble classifying. We have "Store Programs" which would be Pizza Hut night, Kroger 2% of purchases, etc. Would this be under line 6 Special Events and Activities, or Line 8 Other Revenue? This is the first year we have had to file and I want to make sure it is right. Thanks!