To established exactly what I mean, if you've ever pulled a graph on Wolfram|Alpha, you would notice on mouse over of the graph the cross hairs that pop up and a point that traces the graph and displays position data of the point. I have yet to figure out how to replicate that function, the point following a graph and displaying position data (I don't care about the cross hair cosmetics).

Maybe i'm just bad at using the documentation center, and i'm still new with Mathmatica. Web searches did turn up a Mathmatica function called PlotTrace but apparently it was an old function or I don't know what because that returns nothing in Mathmatica 9. Anyone have any ideas? I apologize if this has been asked before, my search turned up no posts related.

P.S. I'm not talking about locator graphics that you can drag where you want it, the idea is it traces the function graph (returning the location of its position X,Y coordinates).