You may find the following sites helpful:

http://mathforum.org/dr.math/

http://www.mathleague.com/help/help.htm

http://www.coolmath.com/

http://mcraefamily.com/MathHelp/

http://www.freemathhelp.com/

http://www.math.com/

http://www.mathleague.com/help/help.htm