It doesn't seem like Mischa Barton has been doing much since the end of The O.C. in 2007. She's had a series of minor roles, but nothing much of note. Last year, she did get a gig in a very strange music video for Willis Earl Beal's "Coming Through," in which she joins the (hopefully fictional) Church of Nobody.
"Coming Through" was released on Beal's 2013 album Nobody knows, though he released a limited edition album, Noctunes, earlier this year.