In case there's anyone reading this that hasn't heard of it before, there's long been a conspiracy theory that the 'real' Paul McCartney was killed in a car wreck in 1966. According to the conspiracy theory, the Beatles feared this would interfere with their rise to fame, so they chose to cover up the accident and replaced the 'real' Paul with a look-a-like that was also a sound-a-like (and apparently a song writer too!).
The whole thing is a little silly and the Beatles have always denied the allegations, but the theory is backed up with all sorts of 'evidence'. The 'evidence' is based on what the conspiracy theorists claim are 'clues' about Paul's alleged death. Many of the clues come from lyrics in their songs or album cover art. Some come from videos, others come from playing certain songs in reverse.
Well the reason I bring this up is because I found a really cool website about this conspiracy theory. It lists all the various 'clues', but it also has a list disputing the validity of many of the clues (the site's author admits he doesn't believe in the conspiracy himself, but made the website because he was always "fascinated by conspiracies."). While many of the alleged 'clues' are silly and some even come from albums released before Paul's alleged death, there are still a few 'clues' that are interesting. The Sgt. Pepper's Lonely Hearts Club Band album has a lot of alleged clues, and the Beatles appear to be attending the funeral of a guitar made of flowers (said to be Paul's bass guitar). I do find it odd that on many of the albums, Paul does seem to be the odd man out in some way, whether he's facing a different direction, wearing a zipper when the others are wearing buttons, or being shown on a red background while the rest are shown on a white background.
While this is one of the sillier conspiracy theories people have come up with over the years, it's nonetheless entertaining. But I guess I'm just "fascinated by conspiracies" too.
Check out the website and all the clues here: paulisdead.co.uk/ (Update: Unfortunately that link no longer works...but you can still find an archived copy on the wayback machine. Not all of the images are available on the archived copy though. There is also a Wikipedia entry if you want more information).