Start your engines! Famous fashionistas are revving up their wardrobes with a staple of biker babes everywhere—leather dresses. Ellen Pompeo wore a fringed leather shift from Alexander McQueen to an N.Y.C. movie screening. "It's got a little twenties feel to it, but the leather makes it really modern," Pompeo told our reporter. Choose a dress with a lower hemline like Pompeo's for a look that is edgy, not trashy. Add killer black heels and you'll be ready for wherever the night takes you—even the back of a Harley.