[Note: I will simply give you the info I have and let you decide for yourself what you think, Also, just because I include a conspiracy does not mean I believe it. It only means I find it interesting enough to include.]
Nixon murdered Joplin and Hendrix
I was originally only going to post about this tonight, but while I was researching it, I came across more things and decided to make this a collection of conspiracies. According to this one, President Richard Nixon was afraid to not be re-elected, so he has some high profile musicians followed and tapped. He didn't like the messages that Janis Joplin and Jimi Hendrix were spreading to voters, so he had their drinks poisoned. This sounds like a ridiculous rumour, and probably is, considering that when Joplin and Hendrix died (1970), there wasn't an election in sight (Nixon started his term the previous year). Although it is true that some high profile musicians were watched, it's unlikely they would have been killed, much less by order of the President. If anything they would have been detained.
Jim Morrison faked his death and is still alive today
On 3 July 1971 the lead singer of The Doors, Jim Morrison, was found dead in a Paris apartment bathtub. No autopsy was conducted, and because of this many theories have popped up over the years. The biggest one is that he never died, but faked his death. He has even been found, supposedly. Of course, the same has been said of Michael Jackson.
Enhanced photo proves Grassy Knoll
Everyone knows the story of the Kennedy Assassination. There have been a thousand conspiracy theories made about it. In fact, the Wikipedia article for the conspiracies I linked just now is longer than the Wikipedia article about the actual event I linked before it. But the one that seems to stick around is that there was a second gunman on the Grassy Knoll. This is one I actually do believe. The evidence speaks for itself. If Lee Harvey Oswald shot JFK from behind, why did the bullet enter from the front and the back of his head explode like that? Anyway, a photo from that day has been enhanced to reveal what many believe to be proof of the shooter in the Grassy Knoll. Known as Badge Man, a figure of a person behind a puff of smoke is clearly visible.