I have recently talked about how to save money and invest tax-free for college using 529 plans. To help boost your savings by making ordinary everyday purchases, there are a few great programs.
One is called Upromise and what it will do is actually link your credit or debit card directly to their system. Therefore, when you purchase from a participating retailer you receive a percentage of the purchase deposited right to your 529 plan as a cashback reward.
Babymint is another service similar to Upromise that may allow you to double-dip on some offers. (Babymint.com is no longer active)
There is also a credit card offered by Fidelity that will reward you 2 % for all purchases made and deposit the rewards directly to your 529 plan. These all are quick to set up and will put your savings on autopilot using free money! I can't ask for anything easier than that.
Assume you earn 2% cashback from $500 of purchases a month. That is a total of $10 earned each month for 18 years. $10 X 12 X 18 = $2160 in total savings.