The Leadership Library on the Internet provides an authoritative list of the new members of the 112th Congress. Access it quickly by hovering over the blue Search button in the top left corner. You can then select One-Click Searches and you'll see the option to select Members of the 112th Congress or Newly Elected Members of Congress. The directory provides a local address for almost all of the new members and an e-mail address for some. This could be a good starting point if you're looking to join their Congressional staff.
Other resources which are following the new members of Congress, include the CQ Press Political Contact Suite and Wikipedia. As always, it's best to verify the information found on Wikipedia with another more authoritative resource, but their coverage of the 112th Congress is impressive.