What other pets should be avoided if you have a cat?

I have a cat and a bird, and the combination can absolutely work as long as you take precautions. In fact, I had two cats when I first adopted Buzzy, but one cat crossed the bridge last August. Anyway, Buzzy's cage is virtually cat-proof - it's about fifty pounds, made of metal, and it sits against the wall with a shelf on the other side, making it almost impossible to knock it over. I introduced everybody slowly, and the cats quickly got the idea that the bird is "friend not food." That being said, I don't let them play with each other, and I don't ever leave them alone together. Buzzy gets plenty of time outside the cage, but he spends most of that time sitting on my shoulder. I also have a spare room in the house which became the "bird room," so Buzzy gets time to play and exercise in there (though he usually chooses to just sit on his playstand by the window and watch the robins outside). I just make sure the cat's out of the room and close the door.