Below is a list of "Significant" Kickboxing Orgs.
Did I miss any ??
United States Kickboxing Association (USKBA)
http://www.USKBA.com
World Kickboxing Association (WKA)
http://www.wkausa.com/
International Sport Karate Association (ISKA)
http://www.iska.com/
International Kickboxing Federation
http://www.ikfkickboxing.com/
World Muay Thai Council
http://www.wmtc.nu/
World Muay Thai Association
http://www.muaythai.com/
United States Muay Thai Association
http://www.usmta.com
Thai Boxing Association of America
http://www.thaiboxing.com/
Women's Kickboxing Association
http://www.womenkickboxing.com/
World Championship Kickboxing (WCK)
http://www.kickbox.com/