One of the things I appreciate most about animals is their ability to change their behavior based on their perceptions of human beings. Some animals are better at this than other, and I think it's fair to say that dogs are one of the most adept species around.
Case in point: the stray dogs in Russia that have learned to use the subway.
The way they describe the dogs hopping on the metro to visit downtown where they "hunt" for food by using their wiles on the humans there, and then riding the metro back home is entirely endearing.
As is this video of a canine passenger waking up just in time to get off at his stop: