I recently found out that the Fuel For School rebate that is currently underway (buy ten Kelloggs items in one transaction and get $10 back) can be done more than once. If you look at the different forms that are available, they have different addresses you mail them in to. You can submit a rebate to each address (p.o. box, etc).
So far, I've found three, but I have heard there are several more. There was one in KMart's flyer a few weeks ago. There is one available to print online, and I have one from a flyer picked up in-store with Kellogg's coupons in it (Thanks Mel!)
If you catch these items on sale, this is a moneymaker. I did the Pop-tarts last week, and will get the Yogos this week. If cereal goes on sale again and there are some decent q's out, that might be another one. Or Eggo waffles, that might be a good one too.
Good Luck finding these!