General

Archaeological Institute of America
Archaeology Magazine
FORVM's Maps of the Ancient World
God Checker
National Geographic
Sacred Texts Archive

Ancient Near East

LookLex Encyclopedia: Ancient World (comprises all of the Near East, including Egypt and Africa)
Oriental Institute's Ancient Mesopotamia: This History, Our History
Sacred Texts Archive: Ancient Near East

Ancient India

Sacred Texts Archive: Hinduism
Sanskrit Alphabet

Ancient China

Ancient Egypt

Sacred Texts Archive: Ancient Egypt

Ancient Nubia

Ancient Africa's Black Kingdoms
LookLex Encyclopedia: Nubia

Ancient Greece

Sacred Texts: Greece
Theoi Greek Mythology

Ancient Rome

Sacred Texts Archive: Roman
UNRV History

Celts

Ivar Gault's Page: the Celts
Sacred Texts Archive: Celtic Folklore

Vikings

Sacred Texts: Icelandic Lore
Viking Age

Maya

The Maya Astronomy Page
(Contains Calendar, Numerical System, Writing, Astronomy, etc.)

Aztec

Inca