I was perusing past threads and ran into this one by Darth Nader, which got zero replies.
So let’s try it again: What “teased but never written” books would you like to read? Personally, I want the missing chapters of Harry Flashman’s memoirs, Scouting For Trolls and Raising Taxes by PTerry and yes, the one Darth mentioned.
You?
True crime writer once said she’d like to write a book about the Stayner brothers – Steven, who was kidnapped and held by pedophile Kenneth Parnell for seven years, and Cary, who was a serial killer. She never did.
Mary Webb never hinted at it, but Precious Bane cries out for a sequel. I mean, so Kester rescued her from the ducking stool just as the townspeople were trying to drown her for a witch … AND WHAT HAPPENS THEN?
ObMention: Dangerous Visions III.
I wanna read Stu the Cockatoo is New at the Zoo.
I would have liked to have read Sherlock Holmes’ Case of the Giant Rat of Sumatra, “a story for which the world is not yet prepared.” (Of course, there have been pastiches by other authors.)
Along similar lines, I’m eager to read Ethel the Aardvark Goes Quantity Surveying.
You’ve got my list . I’d especially like to see how Flashman served on both sides during the American Civil War .
And the Holmes stories casually alluded to by Watson .
Was it Ann Rule?
There are books about the brothers, albeit separate stories.
I’ve seen things about the “10 Worst-Selling Books” and they all had titles like “Lose Weight Slowly By Eating Less And Exercising”. 
Between Rule 34 and Godwin’s Law, I’m sure there’s a book about everything, somewhere.
Samuel Pepys expressed an intention to write a second diary about his later years, but didn’t. He lived 34 more years.
Everything that would have been written by Stieg Larsson, whose Millenium Trilogy was published posthumously after his death at age 50. I consider it to be the greatest literary work of his generation.
Alexei Panshin wrote the (wonderful!) “Anthony Villers Trilogy,” three very thoughtful, very witty, and totally fun novels. At the end of the third book, there is a blurb for the upcoming fourth – which, alas, Panshin never wrote.
John 21:25.
(No, it’s not a variation of Ezekiel 23:20, you goofballs! )
Yes, instead he’s spent forty years minutely rewriting, extending and justifying his peculiar writings about Heinlein.
Christopher Moltisanti’s autobiography “Ton’, I’m Sorry”
Hamster Huey and the Gooey Kablooie
Sorry… it’s on Amazon.
Buttercup’s Baby, the sequel to the Princess Bride.
I won his first book, and gave up after about 15 pages. It just didn’t make any sense to me.