3Dvinci  3D design is a great motivational and instructional tool. It exercises both left-brain and right-brain skills, and appeals to students of all abilities. Our ModelMetricks books contain easy-to-follow projects based on the free Google SketchUp application, to show how to model anything in 3D. Algebasics  This site contains a variety of interactive Algerba help/problems/activities  Archimy   This site has  a service for drawing the graphs of all kinds of functions . With Archimy, you will draw the graph of any function and form, just use your imagination.  The program must be downloaded and is free. Arcademic Skill Builder Our research-based and standards-aligned free educational math games and language arts games will engage, motivate, and help teach students. Click a button below to play our free multi-player and single-player games! Calc3D  This site has interactive Mathematical graph and charting software for geometry and statistics Chart Gizmo This site has an incredible chart builder for any type of data that can be typed or uploaded to this tool Chart Tool  This site is another great tool for creating Charts and graphs  On you can design and share your own graphs online and for free  We support a number of different chart types like: bar charts, pie charts, line charts, bubble charts and radar plots. Concord Consortium This site features free downloadable Math & Science software. CrickWeb  Math interactive tools for white boards Flash Card Creator.  This site from aplusMath allows for the easy creation of  online/printable math flash cards Interactive Simulations for Math and Science from The Univ of Colorado Interactives Interactives" provides educators and students with strategies, content, and activities that can enhance and improve students' skills in a variety of curricular areas Java Math & Science Applets Johnnie's Math Page Links to interactive math tools and activities for students and teachers. Lure of the Labyrinth  This site contains a interesting digital game for middle-school pre-algebra students. It includes a wealth of intriguing math-based puzzles wrapped into an exciting narrative game in which students work to find their lost pet - and save the world from monsters.  This site has a large number of  math puzzles and games.  Many can be used with an interactive white board MathNet  (K-12) MathsNet is an independent educational website providing free mathematics resources to the education community. Its aim is to offer truly interactive resources that are both wide and deep in terms of their applicability and usefulness. MathsNet is not an online textbook. It is interactive, requiring the user to participate rather than be a passive observer. Math Forum  This site contains a listing of a number of additional sites that contain Math interactive simulations. MathNet Number Cruncher Math Playground Welcome to Math Playground, an action-packed site for elementary and middle school students. Practice your math skills, play a logic game and have some fun! Math Problem Solver & Calculator MathTV This site has interactive games and simulation related to math problem solving Math Tool Chest This site has a 'kid' look and feel and many Math related interactive games. MathVids is a website dedicated to providing high quality, instructional, free math videos to middle school, high school, and college students who need math help. Mathway Powered by Bagatrix Solved!™ technology, Mathway provides students with the tools they need to solve their math problems. With tens of millions of problems already solved, Mathway is the #1 online problem solving resource available for students, parents, and teachers. Math Web 2.0 Apps for your iPhone or iPod 
This info is from Karen Brook's blog - Teaching 2.0 - A Professional Development Blog

Online Calculators  Instacalc (also creates charts) Calcr (basic calculator only - powered by Instacalc) e-Tutor Graphing Calculator Create a Graph (creates five kinds of graphs) GCalc: use GCalc2 applet for online calculating GCalc: use GCalc3 to use the Java calculator  Microsoft's downloadable higher level calculator. NumberNut This site has a variety of activities and games that can be used in conjunction with interactive white boards  Random Number Generator  This site allows for the generation of true random numbers.  Teachers could use this for probability and statistics actives as wall as drawings, random sampling and more  RekenTest (3-12)  RekenTest is freeware educational software to practice arithmetic skills.The software supports basic arithmetic operations like addition and subtraction, the multiplication tables and so on, as well as more advanced arithmetic operations like decimals, money problems, percentages and fractions. It can be used for classes or as a homework helper and has lots of options to create the lessons you want. The software offers tasks and working with groups to organize your class. Available in the languages English, Spanish, Portuguese and Dutch. SqoolTools MathFacts (K-6) - Explore all of the best K-6 math tools the web has to offer! From basic addition to geometry and fractions, from virtual manipulates to interactive games, from online calculators and converters to graphing tools. You will discover resources for every math topic you teach. Teachley Mt. Multiplis This game site has students build bridges in the computational math game to help them build their multiplication skills Teaching Time Teaching Tables Visual Math Learning (4-8) This site is a free interactive multimedia on-line tutorial for math students. Its first level, Numbers and Arithmetic , is a pre-Algebra level course suitable for grades 4-8. Unlike traditional textbooks, Visual Math Learning is designed to run on any personal computer with a modern browser. Its user interface is designed to be simple, consisting mostly of push-buttons and objects familiar to casual computer users. Web 2.0 Instruction for Math Educators - a The Journal article