Hi Insomniac, we have thought about the cat thing also. We have a dog who wouldn't be best pleased at that idea! I have never been a big fan of cats, but I must admit the idea tempts me... but then I just think to what my dog might do. Unless of course, they get on famously, but I can't see that somehow.
If you get the cat fairly young it won't be a problem usually, my cat gets along great with the dogs in the area and hasn't ever been bothered. Our cat is a bit of an instigator though.