My cat Marzipan (in my sig) I call furbunny, fluffy butt, fluffnut.
My other cat Paprika is an ornery stray that we've had for about 5 years now. She favors my husband, though she and I get along. But, she will stay in the bedroom all day long, even though I come home. As soon as she hears my husband come home at night, she comes right out and then insists on having at least one body part in his lap as he sits on the couch.
I call her pah-puh-ree-kuh, stinky, and old stiffy (I think maybe she has arthritis, but she has a really funny stiff-legged run, and she's so ornery it seems to fit).
Oh I forgot "the fluffy" for Marzipan; this is her most frequent nickname. Also "gremlin head" for Paprika. Heheh.