Activision Support: The official support website that provides help for CtP and CtP2 players.
Civilization Fanatics' Forums - Call to Power Series: Discussion forum for the Call to Power series.
CtP Modmaker's Depot: Guidelines about the SLIC scripting language. Also several file downloads.
The Land of Hexagonia: Collection of scenarios and modified files for CtP2, but also several available for CtP.
Wes Whitaker's CTP1/2 Modification Site: Home of the Medieval Pack mods for CtP and CtP2.