By simply typing in the function (sans the "y=") the graph shows up. You can rescale the axis with the zoom (the default is both axes but you can scale them individually as well). You can drag the position of the graph around. There is a point which can be dragged to show coordinates and you can put more than one function on at the same time by separating them by commas (they will come up in different colours)
The only limitation that comes to mind right now is that trig functions are limited to radian. I don't see a way to change the x scale to degrees. Let me know if anyone figures out how to do this. In the mean time, happy graphing.