Kellogg's Family Rewards account.
If you're not a member, definitely join! Get exclusive coupons good on cents off one item, which can really help you with your budget as if your store doubles, you will reap greater savings.
Check Slick Deals for a wiki page listing all valid, universal codes gleaned by its members. There are currently 690 valid points available if you're just starting out.
Their instant win game is still going on --- head to Facebook to play.
Don't leave easy points on the table --- be sure to tweet after you play the game. You can tweet daily through end of contest on 12/21.