Food and water bowl - The best bowls for cats are either ceramic or metal (I prefer ceramic because they are cooler and heavier, making them harder to push around). Plastic should be avoided as they can cause feline acne.
Kitten food - Kittens should eat a good quality kitten food, this is higher in calories than "adult maintenance" food. I recommend a mix of wet (canned) and dry. Wet twice a day, and dry left out for them to nibble on. Kittens should be fed kitten food until they are 9-12 months old, and then can be switched over to adult maintenance.
Litter tray - I buy smallish litter trays for kittens, the sides are lower, making them easier to climb in and out of. As the kitten grows, I replace it with a larger tray.
Cat litter - There has been talk of the dangers of clumping litter for kittens, who may eat it, I am still not sure if this is actually true or not, but just as a precaution, I tend to avoid clumping for the first 6 months. Other types of litter are clay, silicone and wood pellets. Find out what litter your kitten has been using, and use that at first, if you want to switch over, transition him slowly by gradually mixing in the new type with the old type.
Cat toys - Kittens have lots of energy to burn and need an assortment of toys to keep them happy, entertained and exercises. The best toys I find are the wand type toys with a feather on the end (Da Bird is a brilliant cat toy). Little toy mice can also be a great source of entertainment to kittens and cats.
Cat bed - This can be enclosed or a donut shape.
Scratching post - A must for all cats who need to scratch their claws. Jackson Galaxy recommends watching how your cat scratches, is it horizontal or vertical? Buy a cat tree or post that matches your cat's scratching style. Trees come in a range of sizes from small to enormous. For Australian cat lovers, I recommend Funky Cat, they make cool looking and extremely sturdy looking trees. We have had one for around 8 years now, and it looks brand new and has absolutely no signs of wear or tear.
Cat flea products and worming medications - Cats should be regularly treated for fleas and worms, even indoor cats can become infected. The most effective products are available from your veterinarian. These usually come in topical (which is applied to the skin on the back of the neck) or tablet form.
Cat carrier - You will need one of these to transport your cat to/from the veterinarian. Place a washable blanket in the bottom for comfort.
Disinfectants - To clean out the litter tray. I use a very mild solution of bleach, which is then thoroughly washed out afterwards. Litter trays should be completely emptied out once a week.
Grooming products - Particularly if you have a long-haired cat, he will need to be brushed daily, this should only take 5 minutes or so. I also recommend a set of human nail clippers to trim the claws every couple of weeks. Cats and kittens generally don't need to have a bath.