Supernatural is a show that is now entering it's 3rd season on CW.
The show follows brothers Sam and Dean Winchester, who travel across the country in a black 1967 Chevy Impala investigating and combatting paranormal events and other unexplained occurrences, many of them based on American urban legends and folklore as well as classic supernatural creatures such as vampires, werewolves and ghosts.
The show is basically a more teen/young adult version of the X-Files. Each week Sam and Dean travel across the US, battle the undead, and usually at least one of the two brothers hooks up.
The storyline is a nice mixture of episodic combined with several underlying story arcs.
There is also a pre-quel comic series called Supernatural: Origins which I haven't picked up yet, but will be doing so. It fills in the early years of how Sam and Dean became "Hunters".
Enjoy! I've seen a couple people say "We should make a Supernatural thead!" a couple times over the past few days, so I took it upon myself to royally mess up it's creation.