I have been a member of UPromise since 2001, pretty soon after they first started. The company I worked for was one of the initial companies where you could earn money back by shopping in the store, so the UPromise team came to my office and explained everything. It sounded like a great program, so I signed up.
Basically, you earn money for your child's college (or for your own student loans) by shopping either through their link online, linking a frequent shopper card (like Kroger, Meijer, CVS) to your Upromise account, or using a linked credit card to shop at places like Exxon/Mobil and Bed Bath & Beyond. You can also earn money using the Citibank Upromise credit card, which is where I've earned the majority of my money. Just a note...we do pay off our credit card every month...there's no point in charging anything for "rewards" if you're paying interest on it :-). You can also invite Friends and Family to help you save.
We have already earned about $1,340 for the boys college using this program. I use my Upromise credit card, I shop through UPromise, and I always use my store loyalty card (even at Meijer where there's no benefit to using it except for UPromise). We also primarily get gas at the Exxon station near our house....of course, it does happen to usually have one of the better prices in the area. I wouldn't shop there if it was more expensive.
Anyway, if you have not signed up already, it's a great program. It's free, and you accumulate money in the UPromise account, and they transfer it every 3 months into a Vanguard 529 (which you have to open up separately though the UPromise site). We're trying to save for the boys college, but it's hard on one income. UPromise makes it a little bit easier.