Go here to read about a lawsuit against Kellogg's that may include you in the settlement.
Basically, Kellogg's claimed that their cereal had immunity-boosters, but there was no scientific evidence to go with this claim. They have agreed to a settlement though. So if you purchased Rice Krispies or Cocoa Krispies between June 1, 2009 and March 1, 2010 you might be entitled to a cash refund.
Go to the website to see all the details.
Thanks to Bargain Briana for this information!