I found the fact that only two people ever saw his dead body was interesting. Obviously, this sparked "he faked his death" rumors, which by many is believed to be the most logical.
I think he had a heart attack from drug abuse. He was found dead in his bathtub and knowing his lifestyle... and what the coroner wrote... Put them together... Heroin + Morrison = Xp
Likewise... I hate heroin. BUT... a theory to his death regarding the overdose was that his girlfriend at the time (Courson) had given him heroin to snort, telling him it was cocaine. What I wondered when read this was: How do you fall for that? Cocaine is white. Heroin is usually a brownish black color. Unless this was some powdered heroin? I've never heard of that but it could be out there since a lot of drugs besides cocaine have powdered forms like that (ketamine, PCP, methamphetamine). Other theories was he OD'ed on a mix of cocaine and alcohol. That's the one I've heard that I would buy the most, considering as far as I know heroin was the only drug he disliked, and he'd get his hands on anything he could (alcohol and LSD for example).
Did you ever hear the story about how "The End" by the Doors was improvised? Well, if you haven't, Morrison was tripping on LSD during the concert and all of a sudden he began playing something the band didn't recognize. They were like "wtf?" at first, but they went along with what he was doing. So the whole song was improvising musically... I dunno if Morrison had planned the words out, but I don't think he did with the part where he's talking about opening a shop and crickets and stuff.