Web2.0calc is a free online scientific calculator. While it won't replace the TI-84 Plus, it can do what your average high school student needs it to do. The best part is, you don't have to use it on the Web2.0calc site because they offer three widgets that you can use to embed the calculator into your own blog or website. You can see one of those widgets in action below (if you're reading this in RSS you might need to click through to see the widget).
Web 2.0 scientific calculator
Thanks to Ann Gregson for sharing the link on Twitter.
Applications for Education
One of the problems the mathematics department in my school faces every year is "disappearing" scientific calculators. Web2.0calc could solve that problem by being placed into teachers' websites where students can use them anytime they like without having to sign-out a calculator for use outside of the classroom.
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