Pileated Woodpecker - for about a year, one of these was living inside a very tall tree at the back of the yard. Even saw him standing in the grass a couple of times! Pretty amazing for such an elusive bird.
White Tail Deer - Okay, these weren't spotted IN the yard, but rather from a bedroom window, in a narrow forested park across the street. In the wee hours of the morning, one of my kids saw several does and a buck not fifty feet from the house. To confirm, we went to that location the next morning and discovered tracks and droppings. Good eye, kiddo!