Knot tying on the web:
International Guild of Knot Tyers - To quote their site "The International Guild of Knot Tyers (IGKT) is an association of people with interests in knots and knotting techniques of all kinds. We have over a thousand members world-wide, from all walks of life, including academics, surgeons, sailors, sportsmen and women, scouters, magicians, farmers, miners and accountants. Membership is open to anyone interested in knotting (whether expert or simply hoping to learn from others)."
Knotting Page - Animated knots including the Turkshead and a lot of knot tying resources - Great site!
Ropers Knot Page - Line drawings and written instructions
Animated Knots by Grog™ - Very nice animated online knot tying guide.
Pathfinders - Official Pathfinder web site.
Scouts - Official Scouting web site.