What are they?
in my neighborhood i can see a brown cat at the corner of my eye and then it just disappears, mom and a few of my neighbors can see it to, i thought nothing of it at first but then i sow this:
Cats are one of the most sensitive animals when it comes to the craft. They tend to see more than other animals into the worlds between worlds. Cats were worshiped in Egypt thousands of years ago but also killed for suspicion of witchcraft connected to the black death in many places just hundreds of years ago and they have never forgotten either of these things. The cat you are seeing could mean different things. I wouldn't worry about it too much. Most likely if this is not a physical but elusive cat then it is the spirit of a cat. Either way be thankful that you saw it for not everyone will.
Azrai, you almost made me choke on my food laughing at that one!
Besides what has already been noted, it could also be a living cat having an O.B.E. (out of body experience) when they are sleeping. Many animals do this. I've seen it a number of times with healthy pets of mine and of friends. They're sleeping, twitching up a storm and someone walks into the room saying they thought they saw the animal running, playing, or doing some other normal activity elsewhere moments ago and then vanish.