Night VFR is a rating which exists here aswell.
The part of it that doesnt do alot for me is that if your VFR the chances are that your going to be flying in a single which if all goes quiet is not going to be alot of fun.
The scenarios mentioned above (lack of visual reference, terrain awareness) have cropped up in NZ in recent times and (assuming its still the case) as of last year some time all night VFR flights on an Air Transport Operation (ie part 135) requires prior approval from the CAA.
The fact that IFR flights can not make a visual approach without the runway lights in sight, nor take own terrain sep. during the hours of darkness says it all really.