Animal Planet have a wonderful application where you can find the perfect dog for you and your family based on your particular wants and needs.
The ten easy steps allows you to specify size, energy level, time available to spend with the pet for play and exercise, affection level, if you have other pets, how trainable and protective the dog should be, how much grooming you are prepared to provide, and the temperature tolerance the dog must have:
There's also a breed selector for all you cat lovers out there:
Cat Breed Selector