"Fancy feathering" refers to unusual feathering that some varieties of chickens have. There are different types of fancy feathering.
Crestedness, for example, is when a chicken has a crest or puff of feathers on the head.
Rumplessness refers to a chicken that naturally (not from plucking or molting) has no tail. Araucanas are rumpless.
Tuftedness refers to feathers up near the ears. They grow out of a fleshy nub called the peduncle. Note that tuftedness is a fatal gene; that means that chickens that get two copies of the gene typically die in the egg before they hatch. Since tuftedness is dominant, just one copy of the gene will gave a chicken tufts. Araucanas are tufted.
Beardedness refers to fluffy feathers beneath the beak like a beard, and muffs refer to more profuse beards that extend further up the sides of the head. These seem to be controlled by a single gene and always occur together. There are many bearded breeds, including Faverolles and Ameraucanas. Silkies and Polish have both bearded and unbearded versions.
Feather-leggedness refers to birds that have feathers (you guessed it!) on their legs.
Vulture hocks refers to long, stiff feathers that grow out of a chicken's thigh (or hock). Sultan is a breed that has vulture hocks.