Some New Yorkers mark the anniversary of the September 11 attacks by going to a memorial service or observing a moment of silence. For the past 10 years, Jeff Parness has been helping others. Every September, Parness brings hundreds of volunteers from New York to help another disaster-stricken community in the United States. It was our way of saying, you know, New Yorkers will never forget what people from around the country and the world did for us in our time of need after 9/11," said Parness. "So that's how the mission started. It was just to pay forward the kindness that we experienced." Over the past decade, Parness' nonprofit, New York Says Thank You, has assisted victims of wildfires in San Diego, tornadoes in the Midwest and Hurricane Katrina in Louisiana. Many of those who receive help are so inspired that they travel across the country the next year -- often at their own expense -- to volunteer with Parness' group and help someone else. The result is a unique disaster-response organization. "All of our volunteers are survivors. They survived, whether it was 9/11 or Katrina or tornadoes. So they all share that common bond," said Parness, who quit his job as a venture capitalist to work on his nonprofit full-time. This year, Parness' mission has come full circle. Last weekend, more than 300 volunteers -- at least half of whom were from outside the New York area -- helped rebuild 13 homes damaged by Superstorm Sandy in October. For Parness, a native New Yorker, the work carried extra significance.