Ours have been

Velocette (named after a kind of old British motorbike with distinctive quiet purr)
Velcro (her clingy sister)
Gunther (named by her previous owner, an opera buff, after a character in Wagner)
Muriel (so-called because whe was grey)
Ishmael (named after the writer Ishmael Reed because he had the same big soulful eyes)
Ishtar (his sister, I'd have preferred Ishfemael but Marion didn't like it)
Mingus (I was on a roll naming black cats after Black artists)
Zeke (named after a nasty Usenet troll on one one of the cat groups, just to annoy him)
Chloe (named by a previous owner)
Splodge (he just looked at me and told me that was his name)
Marblecake (ditto)
Marblecake's kittens:
- Poppy (darker striped like a poppyseed cake)
- Eccles (mostly black like an Eccles cake)
- Gerald (he just looked like a Gerald)
- Siouxsie (weird punkish markings, so named after the singer)
- Pip (named after one of Marion's relatives)
- Ollie (ditto, or short for Apollo the sun god since he's bright golden)
- Polly (she just wanted to be called that)
- Courtney (another punkette and has lived up to it ever since)

I think the cleverest cat names I've ever thought up were for somebody on Usenet who didn't use them. They had two black kittens and were fixated on demoniac names for them. I wanted them named after two Black brother cats with impressive meows, Wynton and Branford.

There is a computer geek on rec.pets .cats.anecdotes who called her cat Cat-5.