More is required of your kitchen floor than any other room in the house. To be totally functional, it has to be non-skid and washable. Like my family, most people use outdoor tiles as it is easy to clean and provides some traction for the feet. As you can imagine, standing for a long time in such a kitchen will be hard on your feet.
If you have a fancy kitchen, the kitchen floors will probably be stone or wood for aesthetic reasons, coated with a thick layer of varnish to prevent scratches. An environmentally friendly material like bamboo can be used to achieve the look of wood.
Vinyl or Linoleum is a sturdy material that can be printed with just about any design in any colour, it is also easy to install by laying over floors like a carpet. Very popular in the 60s and still available today although most people don't use it in their kitchens anymore as the edges tend to curl after several years.
Cork is a new type of environmentally friendly kitchen flooring. It absorbs sound, making the kitchen a quieter place and is softer on the feet. However it is quite delicate, scratching easily and needs to be properly installed in order to be waterproof for washing.
Gelpro makes these kitchen gel mats that provide cushioning for aching feet. It is non-slip, antimicrobial, easy to clean and shock absorbent so things don't break when dropped on the floor. Meant for designer kitchens and yacht galleys it comes in several designs like crocodile skin finish or a relaxed basketweave finish like the above pic. Wouldn't it be great if it came in whole mats to cover your entire kitchen with...