Didn't seem like a thread like this already existed, so I figured I'd try starting one, and ask: what are your favourite babyfur stories?
I've linked to some of my own below, with brief reviews / synopses.
Two Weeks With Ms. Roo by C.S. Fox
A group of teenagers (and one kid) spend time at a ski lodge, only to start (non-physically) regressing. Unfortunately stops just as it gets interesting, and I'm guessing the author has abandoned it in favor of other stories.
Corporate Pride & Timothy by Firemane
About the adult incontinent businesslion Timothy, who gets regularly babysat and treated like a baby by the females at his office. Does include some sexual content, but the scenes are fairly tastefully done.
Jesse by Fieval
The teenage lion boy Jesse gets punished and embarrassed by his mother by being turned into the baby of the household. A bit heavy on the embarrassment (I generally like for the protagonist to have some enjoyment during a story, too), but still very enjoyable. Excellent demonstration of mental regression without calling upon the supernatural.
Spike by Fieval
A lion befriends a husky, who turns out to be more of a baby than he thought. A shame it ends so abruptly.