Wow. I could write a book on this subject. First, there are a lot of different kinds of dogsledding. There are people who do it just for fun, and there are people who do it for work (less often nowadays), and there are people who do it competitively. There are short sprint races of five miles or less, and there are long races of over a thousand miles, such as the famous Iditarod race in Alaska. Different kinds of dogs are best for different kinds of uses.
Several breeds of dogs have been developed over time by native peoples as sled dogs, and these breeds have been developed to serve the natives best in their particular snow conditions and lifestyle, so these breeds vary in appearance, though they do have a basic look in common: Thick furry coats, a wolfish body and head shape, pricked ears, a curly tail.
The Siberian Husky was developed by the Chukchi natives of far northeastern Siberia. These dogs were bred to go long distances fairly fast, and to have a lot of endurance, and to require less food to stay healthy than other kinds of dogs. This was because the Chukchi that developed them were sea-hunters, and in winter they had to use the dogs to cross hundreds of miles of sea ice to get out to their hunting grounds, and then bring back the meat. Since this was a hard life and food was scarce, the dogs were smaller, faster, and food-efficient. Siberian Huskies were imported from Siberia into Alaska early in the twentieth century, and quickly became the most popular breed for recreational sledding and dog racing. They are still very popular today, although competitive sled dog racers have mostly turned to the Alaskan Husky (see below). Pure-bred Siberian Husky teams do still regularly finish long tough races like the Iditarod, though.
The Alaskan Malamute was developed by the Inuit of Alaska. Their needs were different, and they required a different sort of dog to meet them. The Alaskan Malamute is a much larger dog than the Siberian Husky; therefore he is slower, and he requires more food, but he is also stronger than the Siberian Husky. The Alaska natives used fewer dogs on their sled teams, and used them as pack dogs in the summer. When the Alaska Gold Rush started in the 1890's, the Alaskan Malemute was the dog available as a sled dog, and non-native people used this breed for work and for the new sport of dog racing (get a bunch of guys together and they'll find stuff to bet on). The Malamute also found its way to the "lower 48", and is now used mostly for recreational sledding. Malamutes do not have the speed to win competitive races now, but they are excellent in weight pull competition.
Samoyeds are another native Russian breed. They were also used as sled dogs, but apparently not exclusively; they may have also been herding dogs, and they are from a different area of Russia than the Siberian Huskies; farther west and south. They have a longer coat than a Siberian Husky, and they are white. They were imported into England and further developed there as a show dog; this was where it was decided that they should all be white; originally they were other colors as well. They are not used as much as sled dogs nowadays, but some people do use them for recreational sledding, and there is no reason they cannot be good sled dogs, although their long coats are not ideal for the current racing conditions, and since fewer are bred and used for racing there are fewer bloodlines of good sledding dogs to choose from.
In Greenland and in Canada the natives bred sled dogs, too. The Greenland Eskimo Dog is another large freighting dog, and looks very similar to the Canadian Eskimo dog. These dogs are used for recreational sledding in Canada and the upper U.S., and the natives of Greenland still use them for work. They are scarcer than the above sled dog breeds here in the U.S., and are generally too slow to win races.
There are also several different local strains of sled dogs developed by natives in Canada and Russia and elsewhere, such as the McKenzie River Husky mentioned by another answerer, and the Sakhalin Island dog in Japan.
And there are Northern-type breeds that may have been developed from sled dogs in the distant past, but have not been used that way for a long time, such as the Chinese Chow Chow. These breeds are seldom used for dogsledding.
Now we come to the breeds of dogs that were not developed for dogsledding, but got used for it. During the gold rush in Alaska, there were not enough dogs to go around, so people began importing big, strong, furry dogs from the "lower 48" and using them as sled dogs. Dogs that were used this way include the Newfoundland dog and the Saint Bernard, and also any mixed-breed that looked like it could pull a sled and withstand the cold. People are still using other breeds of dogs for recreational sledding, and even for racing in some cases, although some races require dogs to be of a Northern breed. Border Collies have been good lead dogs on competi