Ermm... Here's my two ideas:
Suggestion 1: Knuffel Descriptions
Your feeding someone's Knuffel when you scroll down to the very bottom and see a cute, little description about the Knuffel written by the owner. Sort of like Neopets or other virtual pet sites. Except, it'd be a certain length so there wouldn't be a wall of text underneath all of the Knuffel stats and such. Also, no img codes since posting a lot of pictures and text together might look very messy.
Suggestion 2: Surprise Knuffels
I notice that a lot of people love to guess how the Knuffels will end up looking in their final forms. I can't help but think how funny it would be if a Knuffel ended up being completely different! For example, a Knuffel would grow and grow and look more and more like a rose, and as soon it reach the final level and you're sure what it's going to be, it ends up looking like a rabbit! Except, surprise Knuffels would come without warning and wouldn't be in every generation in order to keep people guessing.
Or, it would always make a funny April Fool's Day gag. <XD