This sketch has a few nice controls for students experimenting with Taylor Polynomials. The order of the polynomial can be chosen, the center, and the function approximating. One of the neat features is that the graphics window will scroll along with the center of the approximation.
There's also an option to show the error over an interval, which is designed to adjust with the zoom level.
I'd love to hear about ideas for other features to enhance understanding of this beautiful mathematics.