I actually submitted my ideas to General Mills about expanding the Monster line to include a cinnamon-flavored cereal with a zombie mascot, and a vanilla-flavored cereal with a yeti mascot... they didn't say anything about the ideas, but they told me that their Monster line gets a great response from consumers every year, so, I don't know.
Remember when the Pebbles cereals used to do things for Christmas? I remember Cocoa Pebbles used to come with a packet of tiny little marshmallows you could sprinkle over one bowl's worth to create a Bedrock Blizzard, while Fruity Pebbles would come in red and green.