Hey Cooltoy,
A couple weeks back you did a photoshop for me:
I just got my car back last week and had the roof wrapped with 3M Gloss Black.
It is simply stunning (unfortunately my crappy cell phone which I took the picture with is not)
Although it is quite simple to do and 3M Gloss black wrap can easily be bought on e-bay and various other direct sources, I had mine professionally done at a Lynx Custom here in Colorado.
This is the same shop that did my tint and love their work.
I'll take some better pictures tomorrow with a good camera and post up if interested.
One word of caution perhaps is that you must have an absolute lint free and paint blemish free roof.
Any wax should be removed for better adhesion and if you have any imperfection in your clear coat a Bar rubover might be a good idea before laying over any Gloss wrap.
You will absolutely see any nick, hair, dust particle etc.
I definitely like how mine turned out.
Here is a general roof wrap:
Audi A4 Black Roof Decal Wrap Installation - YouTube
Hoping this assists!