Free College Savings Plans

I am beginning to learn about the free college savings plans that are out there. The four that I have come across so far are Upromise, BabyMint, The Education Plan, and futuretrust. Basically, you sign up with them and then if you make purchases through them with their paticipating stores, they kick a small amount of money for your 529 college savings plan. I need to do a bit more research on each of them and will likely sign up with all of them to see which one is the best. I'll be reporting on my findings as I do that and hopefully this will also add a few extra dollars into my account.