Sometimes a name doesn't come to you until you've had the cat a while. Our female cat came with the name Sandy, but we've taken to calling her Sumo, due to her passion for wrestling and somewhat chunky shape.
My kitten was named "Heidi" by the Humane Society, and we knew rather quickly that we wanted to change it. Not that I have anything against the name, it just didn't seem like it suited her. I had a hard time coming up with an alternative while my SO kept tossing out names and eventually said Arya and that was it - it felt right for the little spitfire we had adopted.
Margaux had been brought to the local SPCA with a broken jaw. The staff named her...BJ. Needless to say, that wasn't going to work. Celia came in just before Christmas. They named her Mistletoe, which I suppose is kind of cute (but they had it spelled Misseltoe). But I like human names. Hence.
This may not be as much fun, but we always try to name our cats with simple names that they will respond to. That is why we went with Milo and Toby for our boys. Phonetically, they have high and low sounds so they are easy to recognize.
Toby's name was Morgan in the shelter, and not only was it too serious it didn't have a "ring" to it.
Milo is a Russian Blue, and if we were to have named him Cobalt we would have simply called him Coby for short.