Woohoo! Go me, I've been added to a poll!
Seriously, I've got enough leftover fleece (from making scarves and hats for all the kiddoes on my holiday gift list) that I've made all kinds of pet stuff. I made a dog blanket out of colored squares for my niece's puppy and I sewed up some catnip mice for my kitties. My favorite, though, is the chewy braid. Take three thick strips of fleece (about 6" by 1 yd), tie a knot in one end, and braid them together. It makes a nice fat braid that's fun to play tug of war with, and you can toss it in the washer when it gets slimy. If you're really digging the pet thing, braid bits of rawhide into it as well. I made one for my dog a while back, even though he's not a chewer, and he carries it with him EVERYWHERE, it's like a security blanket.