How about the planets, although you may want to skip Uranus.

I used one letter to name 9 kittens once and it worked well for most - Fiasco, Falstaff, Feronia, Fiorella, but a few got names that I wasn't that happy about. I knew their adopters would change their names so it didn't really matter. The shelter had asked a volunteer to name them when they first came in and she gave them all primate names - spider monkey, orangutan, gorilla etc. That definitely didn't work!

Since I was an English Lit and Comp. Religion major I tend to name mine after characters in literature, either prose or poetry, or after gods of various religions both past and present. The shelter where I volunteer hates some of the names I've chosen, like Lochinvar and Catullus because they are "too fancy". However, I hate lots of their names like Samantha Babe (which I switched to Sam) and Bogie for a delicate female cat (I call her Bee). I don't change their names too much so I remember to use their shelter names when necessary.

I have two new cats who are not fosters and have called the big, frightened black tom "Nevermore" because his life of bare survival on the streets is never more, and the disabled cat is "Zazesh" because it means "good at adapting to anything" in Persian.

Enjoy the naming!