One of our Professors used to refer to his Wife's cats as Cat 1 and Cat 2.
I quite like the idea of Ratchet and Sprocket.
There are plenty of potential names after things like herbs: Basil, Bay, Catnip (!), Cinnamon, Dill, Ginger, Jasmine, Lavender, Mint, Nutmeg, Pepper, Saffron, Sage, Thyme (choose any two).
Booze also offers some options, hence Talisker. Guinness is a fairly common name for black cats (especially ones in Pubs).