Supernatural is about 2 brothers- Sam & Dean Winchester- hunting supernatural creatures and trying to save the world from the Apocalypse.
One Tree Hill shows the life stories of a few teenagers from a small town - Haley James, Nathan Scott, Peyton Sawyer, Lucas Scott, Brooke Davis, Skills, Marvin 'Mouth' McFadden, Dan Scott, Karen Roe...- the dramas and the lessons they learn as life goes on.
Fringe: the FBI (Olivia Dunham, Broyles, Charlie, Astrid) teams up with a - formerly institutionalized - scientist, Walter Bishop who was performing experiments on the fringe of real science, and his son - Peter Bishop, an MIT dropout. Together they investigate weird crimes that are seemingly part of a larger pattern of events, and may be connected with a global company called 'Massive Dynamics'.
Tip: this show is a combination between CSI and X-Files, it's quite freaky but the actor's humour and sarcasm makes it a bit more fun.
Gossip Girl is about the Upper East Side teenage life - Serena van der Woodsen, Eric van der Woodesen, Blair Waldorf, Chuck Bass, Nate Archibald - the rich kids; Dan Humphrey, Jenny Humphrey, Vanessa Abrams - middle class kids.
Melrose Place shows the lives of some rich youngsters (Ella, Lauren, Riley, David, Jonah, Auggie, Violet) living in Hollywood and the dillemas/dramas that come up in their lives starting from a crime which takes place in the building they live in.
The Vampire Diaries is about 2 vampire brothers - Damon & Stephen Salvatore - who used to love the same girl -Katherine - a long time ago and who nowadays find a girl who looks just like her - Elena. While Damon causes a lot of damage in his pursuit of reviving Katherine, Stephen tries to protect Elena and her beloved ones from dangers.
Gilmore Girls: Lorelai Gilmore, 32, has a close relationship with her daughter Rory, that they are often mistaken for sisters. Between Lorelai's relationship with her parents, Rory's new prep school, and both of their romantic entanglements, there's plenty of drama to go around. (via IMDb)
The O.C. (Orange County): Ensemble drama revolving around the young adult community of the Orange County, California, area. Ryan, a street-smart teen winds up in the midst of the high-class society of Newport Beach, when he is adopted by the stern but compassionate Sandford "Sandy" Cohen, a lawyer who has represented Ryan in the past for his misdeeds, and his wife Kirsten. Ryan starts getting along very well with his stepbrother, Seth, but their lives get more complicated when they fall in love with two rich best friends: Marisa and Summer.