Click HERE to get a $1/1 coupon good on Kellogg's FiberPlus cereal. After your coupon prints, you will have a chance to register and come back later to get a $2/2 coupon for the same cereal.
There are also boxes out there that say "Try Me For FREE" with a mail-in-rebate. (I saw them at my local Walmart.) You can use the mail-in-rebate for each flavor of cereal (only 2 flavors)............so, if you buy 1 box of each flavor and use a coupon on each box = $2 moneymaker! You will want to do separate transactions (so you can have separate receipts) and mail in each mail-in-rebate in separate envelopes.
I tried the Berry Yogurt Crunch one and it is pretty good!