This site has resources for various Math concepts

Patterns, Functions, and Algebra
This website will allow you to create free algebra worksheets.

General Math Websites
Kuta Software will allow you to create free algebra worksheets.

Homeschool Math has worksheets available for 6th grade math concepts as well as numerous middle school math concepts applicable to many grades

Khan Academy has videos on concepts such as Arithmetic and Pre-Algebra, Algebra, Geometry, Probability, Statistics, and Brain Teasers. There is also practice available with the videos.

The following iXL websites provide practice questions specific to each grade

AAA Math websites provide information and examples including practice problems to grade specific concepts

Brightstorm provides videos on Algebra and Geometry concepts

Brain Pop contains videos, practice, and activities based on many different math concepts

Math Goodies features lessons and worksheets for middle school students

Math is fun provides games, puzzles, lessons, and online activities in such topics as algebra, geometry, measurement, and data

Other: - go to the education tab, under kids games - National Library of Virtual Manipulatives