For the current herd:

Zingo Furrburner--named after a dungeons and dragons character
Oatmeal--that is the color of his furr
Scooter--when he was still outside he would block the door. So we started saying "come on, scoot!"
Turbo--my husband had to pull her off of the turbo charger of his truck where she ran and hid. she was less than 1 pound and severly ill. He swears there is still kitten poop on the turbo charger
Splotch--she looks like somebody took handfulls of paint and threw them at her, causing different splotches of color on her coat
GT--stands for Garage Talker. I had gone out one morning to feed the backyard cat and came in to tell my husband "the garage is talking to me"..took us 3 days to finally catch sight of her.
Momma--just fits, rescued with her kitten
Doodle--the kitten. she was born around the 4th of July. So...yankee doodle dandy came to mind....she gets called Bug a lot for some reason. and Buggly....
Itchy--all white cat with an apparent allergy to the sun. when she was still outside she would be crossing the street and suddenly have to sit IN THE MIDDLE and scratch....