Dynamic Paper

Dynamic Paper allows you to create nets, graphs, spinners, pattern blocks, tessellations, and much more — then export the images for use in Word or PowerPoint, or download an 8.5" × 11" PDF ready for student use.

http://illuminations.nctm.org/ActivityDetail.aspx?id=205

Student Made Math Movies
Collection of student made math movies for different concepts. Pretty amazing site!.
http://studentmathmovies.wikispaces.com

Open-Ended Word Problems
Collection of problems that lend themselves to more than one way of arriving at the answer.
http://fi.edu/school/math2/sept.html

Figure This! Math Challenges for Families
Word problems related to real life. They don't always have all the information but you have to estimate and think. For each problem, there is a hint, other related problems, and interesting trivia. Website supported by National Council of Teachers of Mathematics.
http://www.figurethis.org/index.html

Blackline Masters
This site has every black line master for manipulatives imaginable! Available in PDF and WORD format.
http://lrt.ednet.ns.ca/PD/BLM/table_of_contents.htm

Virtual Manipulatives
This site is amazing! (Thanks, Iain!)
http://www.glencoe.com/sites/common_assets/mathematics/ebook_assets/vmf/VMF-Interface.html

Problem Solving Strategies
This site gives you examples of problems for each problem solving strategy. The site demonstrates the solution and also provides scaffolding for students. It's a great site to share with parents too!

http://thesingaporemaths.com/stratf.html