To balance the vampires I wanted to introduce Werewolves to Oblivion, but so far all I've found are vampire skins applied by wearing clothes (Hardly the same) and a reasonable one called Werewolf: The Awakening which was sadly just the player turning into a dog.
Given what a popular subject this seems to be and how long the game has been out, I refuse to believe nobody has made a decent system for Werewolves.