North American Vexillological Association, http://www.nava.org/navahome.htm

Is your interest in flags flagging? Fire up this website for a heap of information about all sorts of flags.

Do you have a UFO, an unidentified flag object? Use the Flag Detective, which is organized by visual categories like crosses, crescents, stars, triangles, stripes, and diagonals. 

The site also contains articles, a list of recommended books, flags of American Indian tribes, and personal flags.