http://my.hrw.com/math06_07/nsmedia/tools/Graph_Calculator/graphCalc.html
I like as a teacher because it is very similar to the TI-83 and TI-84 model calculators in the steps you need to perform to create a graph -- which makes it a handy tool for students to use at home if they don't have a calculator. There is a "y=" screen, which you can see in the graph, and then a settings page where they need to type in xmin, xmax, xscale, ymin, ymax, yscale just like we practice in my algebra classes. It has a trace feature, and a table feature, and can find the intersections between lines or curves. It can even do graphs of inequalities fairly easily -- much easier than the calculator can naturally, but in basically the same manner as the common application Inequalz which most new calculators come with.
I do wish it had an easier way to capture graphs -- like a copy button somewhere, but I suppose there's always screen capturing tools for that sort of thing. That's a topic for another post.
