I could never limit it to 3. I'm terribly obsessed with the Toy Story saga. I mean, there was that little purple cat in the daycare, didn't say anything, had one closeup moment when Lotso was talking, and I just thought it was the cutest thing ever. I was hoping they'd be like Star Wars and market some of the "daycare extras" anyways.
Some of my favorites are Bullseye, the LGM(aliens), Mr. Pricklepants, Hamm, Rex, Buzz, Woody, Wheezy, Slinky, the Woody's Roundup Critters(again, basically the animated equivalence of an extra, but when Woody's talking real fast and the one just goes "...uh-huh," they left their mark)...