S. M. Stirling has written quite a few series that I feel are interesting and highly entertaining. The General Series A person tries to re-unite his world through military actions after a dark age. They are currently available in omnibus editions (2005) with David Drake The Forge The Hammer The Anvil The Steel The Sword The Chosen The Reformer Draka series The Loyalists, French royals, Confederates and others move to South Africa creating a distopian empire. Marching Through Georgia Under the Yoke The Stone Dogs Drakon The Domination Drakas! Nantucket series 1998 Nantucket mysteriously is transported to classical times. How will they survive with Bronze age peoples? Island in the Sea of Time Against the Tide of Years On the Oceans of Eternity The Emberverse Series Electricity, guns, explosives, internal combustion engines, and steam power no longer work. People from Oregon try to survive after the Change. Part 1 Dies the Fire The Protector's War A Meeting at Corvallis Part 2 The Sunrise Lands The Scourge of God The Sword of the Lady The High King of Montival The Tears of the Sun Lord of Mountains The Peshawar Lancers A meteor strikes the Earth resulting in years of an Ice Age with English-India becoming a world power versus cannibalistic Russians and humans with prophetic powers. Conquistador An American discovers a passage to an alternate Earth where Mayans and Aztecs have not met with Europeans. The story takes place several decades later.