So I did something like this in one of the Vampony group forums. Basically this is a collection of characteristics that writers can look at and use for their Gorgony characters in their stories.

Definition: A Gorgony is essentially a pony that instead of having a mane have strands of serpents attached to the head, as well as the ability to turn other creatures into stone with a glance. Generally all Gorgony are female.

Cosmetic:
-Snakes instead of a mane.
-Snakes for the tail (optional, but could just be the snake tail as a part of the tail).
-Snake body as the lower half (optional).
-Scaly skin.
-Scales covered in slime (optional).
-Serpentine eyes.
-Might slough off their skin.

Offensive:
-Petrifying Gaze: Can be that whoever the Gorgony looks at turns into stone, if the victim looks at the Gorgon they turn to stone, or both have to make eye contact in order for petrification to kick in (feel free to make it that the Gorgony has the choice whither or not they use this ability).
-Venomous Fangs
-May even be able to absorb poison through digestion to enhance their own venom's potency.
-Tusks (if you go off of some Greek myths).
-Might be able to communicate and perhaps even control snakes.

Defensive:
-Immunity or resistance to poison and toxic fumes.
-Can sense magic/magical items (optional).
-Unclean Aura or an Aura of Fear: can be viewed as a blessing or a curse (optional).
-The ability to feel vibrations in the earth. In stone.
-Spike Strands - the scales on the gorgony's snake strands (her mane) grow long and sharp. Kind of like the quills of a porcupine (only more like scales).

Misc:
-Afraid of mirrors as a result of feeling ugly (totally optional).
-Might be cold blooded (optional).
-May need to bathe regularly in order to stay moist and not dry out.
-May also lay down on warm surfaces or out in the sun to heat up.
-Might become carnivorous.
-Her mane might also be able to devour the essence of the ones the Gorgony turns to stone (optional).

Gorgony Venom Qualities:
This pertains to the venom that the gorgony or the snakes of her mane possess. All of these are choices that the author can choose from.
-Lethally Poisonous - resulting in death if not cared for.
-Stone Bite - the wound gradually turns to stone (may require amputation).
-Blindness - shortly after being bitten the victim loses their sight.
-Aphrodisiac - for you sick few.
-Servant/Master Bond - gradually the bite victim begins to feel an urge to serve the gorgony that bite them. It is also optional to give the gorgony and the victim a telepathic connection.
-Conversion - this could potentially result in the victim becoming a gorgony if the appropriate conditions are meet.
1) The gorgony in question is an old and powerful gorgony.
2) The victim is a mare.
3) The victim is willing to be turned (can be optional).
-Snakelings - can mutate the victim overtime into a strange snake like creature that becomes hostile to anything around it except for the gorgony that bite it (great for horror stories).

---

Feel free to make suggestions on things to add to the list. If the suggestions make sense then I'll add them.