USALights.com - lighthouses around the U.S. - check out their section on cards too
Jim Carigan's Lighthouse Page - great links
Lighthouses of the South, by Roger Bansemer
Lighthouses of the Mid-Atlantic
Montauk Point Lighthouse (New York)
Lighthouses in Australia
Rod's Photo Gallery: Lighthouses
Photographer's Guide to New England Foliage
Photo index of thousands of lighthouses, seashores and other pictures from Webshots.com
Dan's Lighthouse Page
Florida Lighthouses
Lighthouse Depot - online lighthouse store
America's Lighthouses
Lighthouse Getaway
Lighthouses Online
The Lighthouse People
The World's Lighthouses, Lightships and Lifesaving Stations - excellent list of links
WorldLights.com
Linda's Lighthouse Page
Night Sentinels - Lighthouses of the World
Great Lakes Lighthouse Keepers Association
The Lighthouse Shoppe
Kenrick A. Claflin & Son - Nautical Antiques Online Catalogue
Official Site of the United States Coast Guard