Hey, Bone. Trekkiegrrl made a free toon sheep. I don't know why she took it down, but she was having technical difficulties for awhile. You might try e-mailing or IMing her, and asking her for a copy of Sheepie. She's ernyoka1 here.

The Japanese sites have some animals. Most are toonish.

If it doesn't have to be posable, there might be something you can use at 3dCafe.