The ones that I liked:

1)The golden compass (just the first book): People's souls walk beside them in animal form called a daemon.

2)Letter Bee (Tegami Bachi): Manga and anime where your postman travels with a companion - sometimes human, sometimes an animal in a steampunky dark world.

3) Chameleon: Enjoyable fanfiction. Sherlock/sentinel fusion where both sentinels and guides have animal spirit guides.

Any other good ones?