You might also want to check out the Fortean Times magazine.
With all due respect, I think you’ve missed the clever 
[SPOILER]The whole point is that the 3 friends make some bullshit up to mock conspiracy kooks, then some conspiracy kooks stumble upon the results of their intellectual game and take it as Serious Business.
None of it is real - we the reader know this, because we’ve seen the bullshit being spun out of thin air in front of our very eyes. The 3 friends know this (even though Diotallevi does start to believe in it out of misguided mysticism/superstition).
The conspiracy kooks do not - they’ve managed to persuade themselves that they’ve known and been agents of The Plan all along, yet are certain the 3 friends know things they don’t.
How can you convince a conspiracy nutcase that his whole conspiracy is 100% homemade hogwash, when he adamantly believes it to be true, believes you to be part of the conspiracy to hide the facts, and will take anything you say to the contrary as misdirection, lie and further proof that the conspiracy is real ?
It’s a catch-22, and a dig at the credulity and circular logic of conspiracy kooks everywhere. Eco’s really, really not fond of them :)[/SPOILER]
“The People v. Lee Harvey Oswald” by Walt Brown is a fictionalized attempt at constructing the trial that might have taken place, had Oswald survived getting shot by Jack Ruby.
As far as building conspiracy theories… this book has hundreds of footnotes, some (or most?) leading to some (small, or large?) degree of (reasonable?) doubt…
It was tedious but necessary. In an ideal world, Posner could have just presented the real evidence and let it go at that. But then conspiracy fans would have presented the pseudo-evidence and claimed that Posner ignored the “real facts” and these prove that Kennedy was killed by the Bavarian Illuminati or whatever. So Posner went ahead and outlined the major conspiracy theories, reviewed the evidence they claimed supported their case, and then showed how weak that evidence actually was. Obviously, he’s never going to convince the hardcore cases - they’ll claim he’s just part of the conspiracy - but by the end of his book, Posner had presented all the evidence any rational person would need to understand the reality of what happened.
JBS-oriented (essentially- Internat’l corporate socialists are working for a New World Order, both building up & “fighting” Communism, and follow a pattern set by the historical Illuminati, which may or may not still exist. Generally avoids veering into anti-Masonry, anti-Catholicism, anti-Semitism, occultism, UFOlogy, but may use sources that involve all these.)
fiction: Taylor Caldwell CAPTAINS AND THE KINGS
non-fiction:
John Stormer NONE DARE CALL IT TREASON
Gary Allen NONE DARE CALL IT CONSPIRACY
Rose L. Martin FABIAN FREEWAY
Antony Sutton WALL ST AND THE BOLSHEVIK REVOLUTION
- WALL ST AND FDR
- WALL ST AND THE RISE OF HITLER
- NATIONAL SUICIDE- revised as THE BEST ENEMY MONEY CAN BUY (US business interests’ build-up of the Soviet military)
- AMERICA’S SECRET ESTABLISHMENT: An Introduction to the Order (Skull & Bones)
James Perloff- THE SHADOWS OF POWER
John McManus- THE INSIDERS
Pat Robertson- THE NEW WORLD ORDER
W. Cleon Skousen- THE NAKED CAPITALIST (a summary of J. Carroll Quigley’s TRAGEDY AND HOPE).
Kobal2 - maybe my attention flagged towards the end, it was a pretty dense book and I must have missed the connection you’ve elaborated on. As I said it’s a good book and I would certainly recommend it generally and particularly for those fond of conspiracy theories, was just giving MHO. 
Oh, I agree - dense and more than a little bit “I’m more cultured than you” at times, but then Eco is often like that, or at least feels that way to me. Still, beats Dan Brown 
Very true, but I’ve enjoyed other Eco books and not found them quite as dense. I really enjoyed Baudolino and found it very easy to read. I definitely agree he makes a habit of waving his large brain around.
Don’t know about the others, but, actually, Pat Robertson’s The New World Order does not merely “use” anti-semitic sources, it cribs from them wholesale while substituting other words for “Jew,” as demonstrated by Michael Lind in his book Up From Conservatism. (Lind, once a National Review editor, broke with the conservative movement partly because he could not stomach the implications of the “no enemies to the right” strategy that required such as Robertson be shown respect at least in public.)
In particular, Robertson copied long passages nearly verbatim from the crackpot writings of Nesta Webster.
Its a Conspiracy! by the National Insecurity Council si excellent and deals with lots of the theories.
My favorite has to be Alice In Wonderland and 9/11 why the official story is a monumental lie by David Icke.
It has everything!
For sheer nutjobbery you really can’t beat David Icke. An ancient bloodline of shape-shifting reptillian aliens has controlled the history of mankind, from ancient times to 9/11. It extends to the British royal family and the Bush family among others. Ritualistic sex abuse, cannibalism, the “real” truth behind 9/11, Icke pretty much has it all. It’s like Illuminautus if the authors really believed what they were saying. You can get most of his books through amazon or at your local brick and mortar shop.
Jim Marrs started out as a Kennedy assassination researcher and spread out to worldwide conspiracies involving aliens.
Seriously, what’s a good conspiracy theory without aliens?
ETA: I note Tamara+ mentioned Icke at the same time I did. Coincidence, or something more…?
Crackpot true, BUT unfortunately, very thoroughly researching crackpot. Now, a lot of people at the time were taken in by The Protocols. Most later had the good sense & integrity to recant. Nesta, however…
Btw, I got her books from friends in the JBS, WITH the caveat to dismiss her references to The Protocols & Jewish plots & focus on her research into the Illuminati & the Jacobins.
It’s good to know your friends have such a healthy intellectual skepticism.
This thread surely would not be complete without a mention of Four Faultless Felons. It’s a fiction, more like a collection of related short stories than a novel, and absolutely brilliant. The premise is pretty well summed up by the title. While an ordinary conspiracy book is all about criminals acting in secret while disguised as good citizens, this one is about good citizens acting in secret while disguised as criminals. The first story, The Moderate Murderer, is perhaps the most brilliant short story I’ve ever read.
For some light-hearted play with conspiracy theories, you might look into the game Illuminati
For that matter, if you’re going to mention Four Faultless Felons, you should also mention another book by G. K. Chesterton, The Man Who Was Thursday. Also, the book The 70 Greatest Conspiracies of All Time is an old edition. It’s now called The 80 Greatest Conspiracies of All Time.
I love Fortean Times, except the US price tag of it is now at something like $11.99 an issue. I sold my back issues of it a while ago on ebay for about $3 an issue.
It is definately one of the funnest Yes, I said “funnest” and interesting reads out there, man.
From the pdf of Object of the Game:
Ok, now who doesn’t want to rule the world? I’m sold and too broke to buy it.
Nuts.