I've always liked the idea of using piano wire to decapitate myself. You tie one end of piano wire around your neck, and the other around something stable and high up. There should be at least 6 feet of slack, so that you have enough time to build up the speed during the drop necessary to quickly slice your head off.
In fact I own a roll of piano wire for this very reason. I was thinking about suggesting this method of suicide to my family recently, so we can all just get it over with.
ER ---> suicide is the best choice though! :-D