Worst way to die? Drowning must also be pretty painful. Any method that is incredibly long and painful and/or scary and/or stupid (like getting run over while crossing the street or something).
I've always thought being buried alive would be the worst way to die. Also the way they used to execute people in old times when they tied each limb to a horse and ran them in different directions is pretty bad.
Being crucified would suck. I read how it tortures your body when I did my capital punishment research report. The stretched position of your arms prevents your diaphram from working properly, but you can breathe if you push up with your legs. Eventually you starve and run out of energy to push yourself up and you sufficate. It wasn't uncommon for victims to be whipped or beaten before hand either which wouldn't help any... Just imagine being nailed on the cross.
I wouldn't want to sufficate or drown. I don't want my limbs torn off. Let's see...I don't want to starve to death. I don't want to die by something stupid, like looking at the Grand Canyon and I trop over my shoelaces so I fall down it.
I think that a better question than "what's the worst way to die" would be "what is the worst way that you could be tortured before you die", unless "what's the worst way to die" was all inclusive and in that case what I just said was completely idiotic. Returning to the main topic I believe that an individual could make someone's death extremely painful and quite horrific if they so desired. However something that vivid and explicit would most likely be inappropriate to describe on this board. I do agree with Travis in the fact that dying alone would be rather horrific in it's own right.
The best way to die is probably jumping out of an airplane entirely naked, along with a bunch of supermodels or something, and having an orgy on the way down. Bonus points for doing it over a major city!