QuickGrapher.com was one of the research projects spun out of Discursive Labs.   One of the most promising projects we worked on, it always felt like a project without an intended audience, but it never really lifted off.  I'm quite proud of the work that Mark and I did, and think it's a tremendously cool project.  

You can use it to embed graphs of any equation within a webpage as easily as a single tag.  You can use it to solve complex equations, functions, etc.  It runs completely in client side Javascript and doesn't require a web connection. it runs on mobile and desktop platforms.  It can display hundreds of thousands of data points and adjust them in real-time.  And now it's open source, BSD licensed, and ready for you to use to escape the tyrannical grasp of Wolfram Alpha.