I'm a guy with short hair (about an inch long) that i've just died pillarbox red. I was thinking of making the back of my head black and then putting in black highlights at the front to make it a bit different...do you think that would work?

I don't see why not. Black and red looks good in any combination.
Post back if you go ahead with it.

You did not happen to see me down the street? I know your idea will work becauase just recently had the same till a week ago. Suggest placing the black in the back so the red covers over the black and pokes out underneath by the base of the neck. The front can be acheived by using foils is another suggestion. Good luck.