A sequel to Donnie Darko is in post-production.
S. Darko takes place in the summer of 1995, seven years after the original film. It follows Donnie Darko's younger sister, Samantha (Daveigh Chase), who, in the wake of his death, has found herself at age 17 with a broken family, mired in feelings of insignificance. She and her best friend Corey (Evigan) set off on a road trip to Hollywood when they are plagued by bizarre visions.[Source Wikipedia]
http://www.imdb.com/title/tt1231277/http://en.wikipedia.org/wiki/S._Darko