is there any way to make annotations snap to a mesh? Is there any way I could use the grease pencil snap to the face of a model/plane? 
For example:


but then if I change the perspective the annotation is floating where it shouldn't
 

It would be much more useful if it could snap to faces, Is there any way I could do this?
Open the Tool Shelf in the 3D View.

Go to the Grease Pencil rider and under Stroke Placement select Surface.



Edit : For blender 2.8 it is in the popover menu.