MathCounts is a national enrichment, coaching, and competition program that promotes middle school mathematics achievement through grassroots involvement in every U.S. state and territory.
MathDL is an online resource published by the Mathematical Association of America. The site provides online resources for both teachers and students of mathematics.
MathWorld is a comprehensive and interactive mathematics encyclopedia intended for students, educators, math enthusiasts, and researchers.
NCTM website contains excellent teacher resources such as lesson plans and learning exercises aligned to national standards.
The Little Animals Center has a wide range of activities for 4 to 8 year olds, including stories, math, and music games.
Mathforum.org is a very informative and useful mathematics site. Features on this site include a student center where students can ask questions, a list of math resources narrowed down by subject, and an online teacher forum.
This link will take you to a self-grading gateway algebra practice test that provides a printable report. The test questions are in a different order at each use.