Lucozade sport is a huge manufacturer of hydration supplements. This website provides information about their supplements and products and the scientific research they have conducted about hydration.
Gatorade has done a large amount of research into the best method to stay hydrated. This link shows the research that led to the production of Gatorade and the products themselves.
Powerade is another company that provides hydration supplements. This link leads to the products available and a small amount of scientific information about the product.
This link leads to the provider of supplements. This website provides a number of hydration supplements. Always be careful when choosing a supplement by checking the ingredients and side effects!
The Australian Institute of sport is a very informative website into sports science. There are links to information into all areas of sport science (including hydration) and the different sports themselves.