Knots Mania

I don't have any good pictures of the boys tying knots to start a knots tying section (maybe in the future). There are several good sites dealing with knots, many contain illustrations.
Knots you should know

Square Knot: The basic Boy Scout knot.  It can be used for just about anything but one has to remember that it sometimes slips.

Sheet Bend: Good for tying two ropes together.  Although it doesn't look it, it can be a extremely strong knot.

Bowline: Another good knot that should be known.  Good for tying lifesaving and that sort of thing.

The Hitches: Slip knots for the most part.  Good for tying tent ropes down or around posts.

Sheepshank: A must for shortening rope.

Lashing: All scouts should know how to lash poles together.  With such knowledge, one can build a good shelter using just axe and some rope.

Ropers Knots Page
A well organized site that contains many illustrations showing how the knots are to be tied. Sometimes there is a little history behind the knot.
The Knotting Dictionary of Kännet
To be honest this page could be better, but it's a start.  More illustrations would be helpful.  This page is in two languages which is always a plus in my book.
Boy Scout Troop 9, Billings, Montana
This is a fellow boy scout troop page.  They have animations to show the knots which is useful.  There is also some history and uses for each knot.
42nd BRIGHTON (Saltdean) Scout Group, East Sussex, UK
Another scout page but does better when it comes to animations.  They offer tips on the tying and uses of each knot.