Hi Lei,
I use some simple silhouettes from an old Illustrator file which I hatch with a solid colour. You can use these as planes and orientate them manually to face the camera but I don’t know of any sketchup-like way to do this automatically.
Good idea though, it would be handy if there was a script which could take the surface normal of a selected object/plane and orient it toward the active camera along the X Y axis.
Andy