wrote about the new graphing calculator Android app offered by Desmos. In that post I neglected to mention that Desmos also offers a Chrome app. The Chrome app version of Desmos works like the web version. Along with all of the graphing functions Desmos allows you to share your equations and graphs. Desmos graphs your equations as you type them and redraws them as you alter your equations.
Graph.tk is a free online graphing utility that is also available in the Google Chrome Web Store. Graph.tk allows you to plot multiple functions through its dynamically re-sizing grid. To graph an equation on Graph.tk just click the "+" symbol to enter a new equation. One thing that isn't clear the first time you use Graph.tk is that you need to delete the existing default equations before you start.
Applications for Education
If your school has gone 1:1 with Chromebooks, Desmos and to a lesser degree Graph.tk could be good alternatives to trying to keep track of TI-84's or other graphing calculators.