Dr. Fate here before in relationship to Zatanna.
Over at the Tower of Fate there are some new Zatanna/Fate "crossover" images and posts.
DC Dark Characters
DC Mystic Cosplay
More images are here: http://rarityfleur.deviantart.com/
Dr. Fate Art featuring Zatanna
With more images here: http://mantisstudiocomics.deviantart.com/
Despite their similar powers I have not found too many stories that feature them both.
There is the Young Justice episode, but I can't find anything in the comics proper.
So here are some of YJ Zatanna as Dr. Fate,
Zatanna's Fate by *inspector97 on deviantART
Zatanna is Doctor Fate by *Glee-chan on deviantART
Doctor Fate by ~King-of-Losers on deviantART
Doctor Fate Zatanna. by ~Hero-sketch on deviantART
Fated by ~Sherlockmysteries on deviantART