Mobius: because when she was a kitten she curled into a position that made me think of a Mobius strip.

Diva: came with the name

Diamond: she has a white diamond-shaped locket on her chest

TicTac: black with a white Tictac shaped spot on his chest

Smokey the Younger: her temperament is EXACTLY like Smokey the Elder's was!

Bosun: came with the name, former foster

Bubba: Used to be Blubb, hated the name. He's a big sweet no-neck cat, so became Bubba. Another (failed) former foster.