There are countless archaeological sites exist in
Easter Island or Rapa Nui but the popular sites are Rano Raraku,Ceremonial village of Orongo, Ahu Moai, Ahu Tongariki, Tahai-Ko Te Riku Complex, Ahu Huri A Urenga, Ahu Akivi, Ahu Ature Huki and Ahu Nau Nau. You can visit more sites through "Archaeological Tours", a travel company which organizes archaeological trip to Easter island and I have heard that they are conducting "An Archaeological Study Tour" in Northern Chile & Easter Island from October 30th to November 16, 2008, so I think your sister will call them on 1 866 740 5130 and make arrangements for her trip. hope this helps!