A lovely Geogebra applet that graphically shows how the sine and cosine functions are generated from the unit circle. From The Lawrenceville School Mathematics Department Web Resources.
http://mathplotter.lawrenceville.org/mathplotter/mathPage/sine.htm

Mad Minute activities are warm-up and review activies. This one reviews the exact trig rations. Drag in the stickies as visual aids.