The following are some sites worth visiting:
Legendary Lighthouses - This is the companion website to Legendary Lighthouses, a PBS series about lighthouses and the places where they are located.
New England Lighthouses: A Virtual Guide
Night Beacon Lighthouses - On-line lighthouse picture tour and history guide for lighthouses, lightships and life-saving.
The Lighthouse People - This site provides photos of lighthouses. It states that it provides photos of all the lighthouses in the US.