Morgan Lomis shares an Arc tracer tool which is is a great substitution for physically drawing out animation arcs on your screen right in Maya. Of course the new Maya 2012 has an updated motion trail that will allow you to show and animate paths right in the viewport, but ml_arcTracer is a good solution if you are using 2011 or under. It creates a thick line to represent the path of an object, either as an overlay on your camera view, or in world space. It’s a bake process; like a marker it doesn’t update interactively. Lines are colored randomly, to distinguish between multiple traces. Frames are marked along the arc as black dots, with keyframes colored red, and the current frame is highlighted. Download the Maya ml_arcTracer here.

ml_arcTracer.py is basically to imitate the benefits of drawing on your screen with a dry-erase marker. Its similar to creating a motion trail, but you can create it as an overlay on the camera, so that you can see the path something is travelling in screen space. It uses paint effect to draw the line, so its nice and thick. Frames are ticked black, keyframes red, with the current frame highlighted.