My dog's name came from the old rhyme that starts, "Monday's child is fair of face. Tuesday's child is full of grace. Etc." Well, nobody was ever going to mistake this puppy for a ballerina, even at 3 months, so Tuesday was out as a name. But she WAS very pretty, and so she became Monday.
My other dog was already Katie when I adopted her, and it fit perfectly. Somehow it morphed into Katie Mae when I wasn't looking.
My cat, Marco Polo, Intrepid Explorer, was a very ...adventurous kitten. How he lived to grow up, I'll never know. His sister was such a gorgeous calico that I wanted a name to play off her coloring. But every other calico seemed to be named "Patches," and there's no way I'd name an animal "Cali" because it sounds just like "Kali," the Indian goddess with all the arms and skulls and blood and such. So I named her after what she looked like: PatchWork Quilt Kitty, and threw in some e's for pronunciation. Thus--Pweeqk.