I'm fascinated by the current research into animal therapy. That is: therapy for humans that is undertaken with the use of animals. Like cats and dogs (and llamas!) visiting nursing homes and hospitals.
It goes beyond that, too, with therapists using the animals sort of to distract young patients, get their guard down a bit, to open up to treatment. And there are programs for returning veterans with PTSD too, where shelter dogs are trained to help (or the veterans themselves do the training, which is apparently therapeutic too), and apparently the training is less intense and less breed-specific than for service dogs, so there are more (and less expensive) dogs available for the training.
Nice article here, from NPR: pet therapy.