Is it possible (using 3D Studio Max) to render only the shadows in a scene as they fall on a flat plane? The reson I want to do this is I have to create a light map for a 2D game I am working on. When the creatures walk over the dark areas of the light map their brightness will change.

You could try this:

Make a plane underneath the object to recieve the cast shadow.

Right click on the object you want to cast the shadow. Properties. Then uncheck the box about "Visible to Camera".

It wont display the mesh but it will still cast a shadow.

You might get the best results, if you also use the Matte/Shadow for the plane.

Awesome! Thanks for the help.