TAMinations Best animations of all levels of square dance calls. This is part of the Tam Twirlers SD Club and includes complete animations (see all calls from Basic to Advanced).
SaddleBrooke Squares Videos Provides videos of a basic square dance demo and then 18 Mainstream lessons and 10 Plus lessons. An excellent resource for beginning and experienced dancers.
CALLERLAB International Assoc of Square Dance Callers. While geared towards callers, there is a lot of helpful information within the site on Calls, definitions, and other info associated with Square Dancing.