Grease Pencil

Is it possible to have a grease pencil tool? I would like it if it has two modes like:

1. Draws on the viewport, like for example making a silhouette.
2. Draws on the mesh so that when model I would not miss my topology.

also is it possible to add layers and different kind of colors(basic).

this can also be use for teaching purposes.

Thanks.

EDIT: Also is it possible to add a hot window for the smooth group. Thanks.

A grease pencil feature would be cool - have seen some really nice uses of this from the Blenders folks.

Also, lest the added request at the bottom be missed:
+1 to Smooth Group Hot Window request

Bump.

I really wish this to implemented.

Thanks.

I haven't got time to look at it yet. It may take quite a while for me to figure out how to do it.

I never used grease pencil, and never felt the need to. So I wonder if it is that much of a deal? I imagine I can model without it, but what I would need is a proper UV editor. But ok, lets keep this thread about grease pencil. I just think it's a nicety and not a necessity.