OrigamiUSA Originally the Friends of the Origami Center of America, OrigamiUSA is a national organization for origami enthusiasts. Its events include monthly Folding Sessions at the American Museum of Natural History in New York City and a yearly Convention.
Joseph Wu's Origami Page One of the best websites devoted to origami. It includes many pictures, diagrams, and links.
http://www.ohayosensei.com/books/origami.html Contains a large list of origami books.
Tom Hull's Origami Math Page This site has instructions for models, mathematical analysis, and links.
Origami and Education and Therapy Bibliography A bibliography of books and papers on related to the topic of origami usage in education and Therapy.
Chris Palmer's Tesselations Pictures of tesselations made with paper.
Jim Plank's Origami Page This site focuses on modulars and has pictures, diagrams, and links.
Gretchen Klotz Westlight's Origami Page This site describes the Okinawa Crane Project and includes pictures of paper boxes and other things.