I dont own any pets (would like to, but time constraints stop me) but, I am appaled as to what many feed their animals. All these corn based diets are making for some fat animals.
But, on the note about what to feed your cats, I found a cool article on Mark's Daily Apple about it.
He goes into ways to introduce such a diet to a cat, timing, and the taurine problem.
The Primal cat diet should (roughly, not hard and fast) approach the approximate dimensions of your typical prey animal:
80% Muscle meat (including fat, skin, tendons, sinew, cartilage)
Fish – especially oily fish like mackerel, sardines, or herring (which thankfully are a lot cheaper)
10% Organ meat, half of which should be liver
10% Edible bones (as opposed to a huge beef shoulder or something)
Whole fish with small bones
Chicken/turkey necks and wing tips