To have one master switch to turn off all lights - you might not enjoy the amount if re-wiring you'd have to undertake.
The shorter alternative would be to...
1) Hit the already installed switch to turn off your headlights & parking/running lights.
2) Hit the already installed switch(es) to turn off your radio / electronics.
3) Install one switch to disable the brake lights so you could press the brake pedal but not get the lights [or just don't use the brake pedal] (legality issues might be there for on-road use).
4) Edit: door open dome lights, if you have them (you don't have your vehicle listed in your profile) might be an additional concern - if you wish to open your doors w/o light(s).
5) Edit2: Dang - didn't think (again, what vehicle do you have) about certain dash lights - Check Engine, Oil Pressure, Low Fuel, Upshift indicator...
Again, how much wiring are you looking to tend to get what you want?