The national math coaching and competition program for 6th, 7th and 8th grade students. http://www.mathcounts.org/
Math Dictionary for Kids http://www.amathsdictionaryforkids.com/
Interactive Math Dictionary http://www.mathwords.com/
SuperKids Math Worksheet Creator http://www.superkids.com/aweb/tools/math/
Algebra Homework Help -- People's Math! http://www.algebra.com/
Algebra Help http://www.algebrahelp.com/
An amusement park of math designed for fun! http://www.coolmath.com/
Doctor Math http://mathforum.org/dr.math/