Diet is the foundation of good health. So many of the diseases that afflict our cats these days e.g. allergies, urinary problems, obesity, inflammatory bowel disease, etc. can be traced back to a poor diet. An appropriate i.e. fresh balanced raw diet, will keep your cat happy and healthy. Unfortunately, what cats should eat (meat, bones, and organs in the ratio contained in small cat prey), and what is contained in commercial dry and canned cat food are not the same.

Now, without belaboring the point, we'll just move on to what one should feed as opposed to what we shouldn't feed our cats, and refer you to this excellent paper by a Harvard Law School student uncovering the ugly aspects of the pet food industry including what goes into the making and selling of pet food: http://leda.law.harvard.edu/leda/data/784/Patrick06.html

Unlike humans and certain other species, cats have very specific and rather narrow dietary requirements. A cat’s ideal diet is one that is at least 95% from animal sources. It contains a high amount of protein and moderate fat amount combined with low fiber, low carbohydrates, and high moisture content.

Rawfeeding ain't rocket science, so don't let it intimidate you, but strive to feed small cat-appropriate animals/birds that are balanced unto themselves so you don't have to hope for balance over time. If however, whole prey is not for you, then grind a complete animal/bird and aim for a Calcium to Phosphorous ratio of 1.2 - 1.4:1.

Keep it simple by following a few basic guidelines:

• Meat, organs, bone, and taurine are absolutely essential. All preferably raw; however a cooked diet is better than commercial.
  
  
• Any supplements you use should be from animal sources e.g. fish oil, and not flax or hemp seed oil for Omega-3.
  
  
• Meat, organs, and bone contain 0 fiber. On a whole prey diet, cats would ideally consume some fur and feathers. Some fur/feather might need to be trimmed off since some cats' digestive system have trouble with them. Next best choice is to add high-moisture low-glycemic index vegetables @ around 3-5% of your cat's diet. If your cat is allergic to vegetables, then psyllium or rice bran (~ 1/16 - 1/8 teaspoon daily) are okay again depending on how well your cat handles this fiber source.

• Avoid grains completely as a large % of cats are allergic to them. At best, grains are an unnecessary source of carbohydrates for cats, these erstwhile capable guardians of ancient Egypt's granaries.

• Cats need preformed Vitamin A as they cannot convert beta-carotene into Vitamin A. Interestingly enough, 2 studies have shown that although cats absorb beta-carotene presumably obtaining an anti-oxidant benefit from it.  Of course they do not convert it to Vitamin A, so meat and organs should supply cats' vitamin A requirements, not vegetables.

• Cats cannot convert Tryptophan into Niacin, so need preformed Niacin (B3). Meat particularly chicken breast contains healthy amounts of niacin. 
  
  
• Try to feed the entire animal, not bits and pieces because nutritional profiles (including taurine) vary among body parts of the same animal, not just among animals/birds.  Rotate among a variety of animals and birds, don't feed the same thing day in and day out because some meats e.g. chicken and turkey have lower potassium levels than venison and rabbit.
  

• Cats need ample amounts of amino acids Taurine and Arginine, both of which are available in meat.

• Use herbs and nutritional supplements sparingly as a significant number of the herbs and supplements good for humans are not safe for cats.

Benefits of a raw meat-based diet

• Loads of energy
• Elimination of stomach problems such as diarrhea, vomiting, and constipation
• Shiny coat
• Improved muscle tone
• Smaller stools with virtually no odor
• Clean sparkling white teeth
• Nice clean breath
• Elimination or decrease of itching and allergy problems
• Maintenance of ideal urinary pH (6 - 6.5)
• Strong immune system leading to better resistance to infections
• A lot less shedding, with rare hairball sightings

Safety Concerns

Appropriate care must always be used when handling raw meat, and proper thawing techniques should be utilized. Barring such mishandling problems, neither salmonella nor e.coli is a problem for cats. This is because a carnivore's intestinal tract is about a third the length of a human’s which allows meat to enter their digestive system and exit in about half a day. Their strong digestive juices with a high hydrochloric acid percentage get to work on the meat, and digestion happens quickly before meat can putrefy in the intestinal tract.

Unlike herbivores, cats do not need a long intestinal tract necessary to allow the body to break down and fully digest vegetables and grains. However, most commercial cat food contains grains and vegetables which our little tigers are ill-equipped to handle. Cats have virtually no carbohydrate requirement and get their energy from fat and protein.

References

"Idiosyncratic nutrient requirements of cats appear to be diet-induced evolutionary adaptations", Morris J.G. Nutrition Research Reviews, Volume 15, Number 1, June 2002, pp. 153-168.
(note: they keep moving this article, and although I try and stay on top of it, please google it in case the link isn't working; here's the abstract, which seems to stay put:)

"Cats Absorb ß-Carotene, but It Is Not Converted to Vitamin A", Florian J. Schweigert, Jens Raila, Brigitta Wichert and Ellen Kienzle, J. Nutr. 132:1610S-1612S, June 2002.

"Dietary ß-Carotene Absorption by Blood Plasma and Leukocytes in Domestic Cats" Boon P. Chew2, Jean Soon Park, Brian C. Weng, Teri S. Wong, Michael G. Hayek and Gregory A. Reinhart Journal of Nutrition. 2000;130:2322-2325.

"In summary, these studies provide the first available evidence that domestic cats can readily absorb ß-carotene across the intestinal mucosa. ß-Carotene also is taken up by peripheral blood leukocytes and is distributed into subcellular organelles, notably the mitochondria. In the leukocytes, ß-carotene may play an important role in maintaining their structural and functional integrity. Therefore, some aspects of the biokinetic uptake profile of ß-carotene in domestics cat are similar to those of humans. This similarity suggests that domestic cats may be an appropriate animal model for studying ß-carotene absorption and metabolism in humans".

Intestinal Lengths and Transit Times for Digestion: mean retention time of 13 hrs" (another article that keeps changing URL)

Debra L. Zoran, DVM, PhD, DACVIM, "The carnivore connection to nutrition in cats', JAVMA, December 1, 2002 (Volume 221, No. 11)