I want to draw an image on top of an object I have created with the grease pencil. When I then select render the object will appear, but it will not show the lines I drew with the pencil. How can I get the grease pencil lines to show up in the render?
It seems that at versions of Blender prior to 2.78 the only way to directly render the Grease Pencil is using the OpenGL Render option - since this effectively renders the scene as it would be viewed in the viewport.
However, in the Grease Pencil panel there is a Convert option which can convert your Grease Pencil layers into a path or curve. This can then be used to generate geometry (eg, by setting a Bevel Depth in the curve properties) and this can then be rendered.
It does appear that there are plans for a significantly improved Grease Pencil at later versions as detailed here https://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.78/GPencil and this includes an additional GP_Layer when rendering OpenGL to multi-layer EXR.