Found some things that are not really worth their own threads but are mildly interesting.
In the webcomic Darwin Carmichael is Going to Hell there is a bit where a girl is turned into a cat to take part in a circus of people turned into animals or something. Arc starts here:
http://dcisgoingtohell.com/280-the-magic-hat-part-i/ and the transformation is about 3 pages after that.
In the anime Flying Witch there is a character who was turned into a dog girl by magical chocolates. You see her for the first time in episode 4, and although the transformation is offscreen there is a nice scene of her waking up and reacting to it about 12 minutes into the episode.