Sleeping pills are probably the most painless, you just pass out. Overdoses of drugs such as Acid,LSD,and other phyco drug is another stupid way to go, and if you live through it you are a vegetable for the rest of your fucking life. In the old west they used a more or less 'painless' way of hanging. A relitivly good and graphic way to go. Very stupid unless you have a high cliff or mountain.
People usally try to pull out at the last second, and end up paralized for life.
Not bad, as long you have a good current. Go to your local power substation and ground yourself to something, and as soon as you touch the ends of those big semi-condutors, you're history. Same as drugs. Usally reserved for Sickos, a very painful way to die, and you watch yourself bleed to death. Pretty beat way to go.