
An American breed that is very similar is the American Eskimo dog, or Eskie to his friends(though always white or Biscuit coloured) , here is a picture and the AKC standard
http://www.akc.org/breeds/recbreeds/amesk.cfm. Try a google search on these. They seem to be of similar temperament to German Spitz, and seem to be fun loving enjoying Agility etc.
Another breed is the Japanese Spitz, though I beleive these are somewhat sharper, and always white.