A movie about three, possibly four, girls in high school, where one of them is an 'actual' witch, or a 'good' witch, but there is this girl with dark hair who wants to become a witch for the wrong reasons. I remember a scene where they're on a beach, where the dark haired girl calls to the witch gods, or something, to get her powers, then the next morning there's a washed up shark on the beach. The movie ends with the dark haired girl ending up in an insane asylum. What is this!

I've seen this movie. One of the girls likes this boy but he doesn't feel the same way and she sets a spell which results in him being obsessed with her...

Yeah good movie, but sorry I cannot remember the title either :o/

The Craft (1996) (http://www.imdb.com/title/tt0115963/)

That movie is called "The Craft". I think that movie had Neve Campbell and that girl Fairuza Balk that played in the movie return to OZ when she was a kid and later the water boy.

I hope this was the answer your looking for.

THE CRAFT