I somehow earned two secret hats. I understand that the reason for attaining the secret hats is meant to be unknown. So is the existence of the secret hats also meant to be unknown? Or is there a link to a list of secret hats?
Secret hats are meant to be a surprise. But... Winter Bash 2014 Secret Hats is a Meta.SE thread where all the secrets are already spilled by the users who figured out what triggers each hat. (At least, each hat that has been awarded so far. One can never know for sure whether there is something super-secret that nobody has earned yet.)