Science has a story about the use of domestic dog breeds to understand the genetic basis for various behavioral, morphological, and disease related traits.
The Geneticist's Best Friend
Science 21 September 2007: Vol. 317. no. 5845, pp. 1668 - 1671
Many dog breeds are like large inbred families, and many times have known genealogies, so that each breed is, as Elaine Ostrander describes it, "like a mini Iceland or Finland". Along with Carlos Bustamante, they are developing the dog equivalent of HapMap: CANMAP (didn't see it online yet)
By the way, Science has several other papers on dog genetics:
Genetic Evidence for an East Asian Origin of Domestic Dogs
Genetic Structure of the Purebred Domestic Dog
A Single IGF1 Allele Is a Major Determinant of Small Size in Dogs
Man's Best Friend(s) Reveal the Possible Roots of Social Intelligence
I think there is a lot of potential here... it sounds like European scientists are leading the effort. One of my favorite examples is the foxes in Russia who were bred to be docile and at the same time developed a lighter coat. I'm not sure exactly what's going on there but it seems to be uncovering some kind of pleiotropy: the genetics of behavior somehow linked to the genetics of coat color.