Astral Projection

Out of body experience The experience of floating outside of, and in some cases, seeing one's physical body from a place outside one's body. This usually occurs spontaneously and is linked to dangerous circumstances, a dream-like state, a near-death experience, or use of psychedelic drugs. In this episode Dean tells Tessa that if they are having an out of body experience it means that they are spirits of people close to death. Other names for an out of body experience are bilocation, crisis apparitions, and fetches. – Pad of Definitions (2.01 In My Time of Dying), Official Website

Apparences

4.15 Death Takes a Holiday

Dean and Sam arrange an intentional out of body experience when they have psychic Pamela Barnes send them to the astral plane so that they can investigate their case. Once there, they are vulnerable to salt and iron, like ghosts. However, this allows them to see the Reaper Tessa and they posses all the powers of normal ghosts. With the help of Cole Griffith, they learn how to use them properly and save Tessa from Alastair who is captured by Castiel while chasing Dean. Sam is pulled back to his body by Pamela after a demon attacks her, but Dean stays a spirit long enough to help Tessa crossover Cole.

8.15 Man's Best Friend with Benefits

As a witch, James Frampton is capable of astral projection and uses it to spy on his rival Ed Stoltz at the police department, projecting into Sam and Dean's minds what he sees. Using astral projection, James, Sam and Dean learn that Stoltz is building a case against James for the murders that have been happening recently and find a clue to who is framing him: the familiar of his friend Spencer, Phillippe LeChat is the witness against James that Stoltz is using to build his case on.