Shades of the '60s ... musicians David Crosby and Graham Nash have announced they will play a concert to support the Occupy Wall Street protesters camped out at Zuccotti Park. The free acoustic set on site this afternoon will feature—what else?—protest songs. Rock-and-Roll Hall-of-Famer Crosby of stalwart hippie band Crosby, Stills, and Nash, visited the park last week, reports AP. The musicians are part of a growing cadre of celebrities getting behind the Occupy protests across the nation, from MC Hammer and Kanye West to Yoko Ono, Mark Ruffalo, and Penn Badgley. (More Graham Nash stories.)