Great task-based (and test) assessments! Emphasizes mathematical process expectations like communicating, reasoning, selecting tools, etc. Free to use unmodified. Primarily up to grade 10 level. Sorted by americal Common Core Standards.
This Add-In for MS Word and MS One Note integrates many features of Microsoft Mathematics with microsoft's equation editor (Word 2007 and 2010). Most importatnly it produces attractive graphs which would be great for test preparation, but while it has several controls for window, scale, etc., I have not found any for line thickness or colour. Work around this by converting graphs to greyscale, increasing contrast, and decreasing brightness via Picture Tools > Format after inserting a graph.
Microsoft Mathematics is a free graphing calculator and CAS for windows. It has an equation solver that shows a step by step process, and in my quick test it also gives restrictions on solutions. Will integrate and differentiate expressions, work with matricies, and more.
An amazing resource for non-linear physics research. Gravel roads to stalactite formation to pouring syrup - physics (and mathematical) analysis all here
This site expains the mathematics behind images, and occasonally supplements with applets, animations, or teaching materials. Still a little sparse, but what is there is well done.
Timon Piccini's video resources based on Dan Meyer's 3-acts format. A good fit for both inquiry and authentic learning approaches. These videos fit well for Grade 9, and some stats ones are on the way (available now via his Vimeo channel)
A great site - essentially an interactive textbook for Grade 9 Alberta curriculum. Lots of java applets presented within written passages set up to lead through a progression of knowledge/skills. Resources for a number of other courses if you hit the [Home] link at the top of the page, but I have not looked through other areas of the site.