It's not every day that ZZ Top's Billy Gibbons wonders over to Wall Street, but he did today to help promote a benefit concert Friday night in New York. The group Wall Street Rocks is holding a concert to raise money for military veterans and first responders. Gibbons joins other performers at the event, including John Popper of Blues Traveler, and Matt Sorum of Guns N' Roses. The group Wall Street Rocks is a collaboration of employees in the financial, technology and entertainment industries. The concert is being held at the Highline Ballroom in New York.