Petfood Direct
I have been ordering food from Petfood Direct for over a year. The service is very good, and there's a lot more here than just pet food.

Waggin' Tails
Waggomtails sells premium food, treats, and more for cats and dogs. Some products are rated. Food has nutritional information, but the treats don't. You can also request samples that a vet will tailor to your pet's needs; you just pay for shipping.