To request a duplicate approval notice, to request an approval notice be sent to another U.S. Consulate, or to request an approval notice be sent to a U.S. Consulate for derivative visas for family members.
http://www.uscis.gov/portal/site/uscis/menuitem.5af9bb95919f35e66f614176543f6d1a/?vgnextoid=dd153591ec04d010VgnVCM10000048f3d6a1RCRD&vgnextchannel=db029c7755cb9010VgnVCM10000045f3d6a1RCRD