Territorial, island, political, and historical flags.
http://www.itsanhonour.gov.au/symbols/flag.cfm
Its an Honour: Flying the FlagGuidelines on flying the flag and using it commercially, with images and template.
http://flags.nationmaster.com/
All the flags of the world on one page.
http://www.nava.org
North American Vexillological Association (NAVA)Nonprofit organization dedicated to the promotion of vexillology, the scientific and scholarly study of flag history and symbolism.