Andrea Frick has started a new blog on the Best Friends Network named "Clicker Training: No More Homeless Pets." On it she answers questions related to adoption and training, and for very good reason. As she puts it:
Many animals that end up in shelters have little or no training. Training can help to make an animal more adoptable and more comfortable interacting with people. Good training can build confidence in a shy animal and calmer behavior in animals that show stress. It can reduce aggression and build great relationships between animals and the people that train them.
If you have questions about training a shelter animal, this is a great place to get your questions answered.