In one of the Deathlands books, a character tells a story of little “Stevie King” who has a run-in with gypsies quite similar to what happens in Thinner
In the book War Day authors Whitley Strieber and James Kunetka are the protagonists of their own book which is supposedly set after a nuclear war. They travel across America and encounter some real people, including fellow author Chelsea Quinn Yarbro.
That was Spielberg? I thought it was supposed to be Martin Scorsese.
…And I certainly appreciate the theft of my thunder. I’m taking my ball and going home now.
PS: It was Jethro Tull in the Postman. I should know; I have all his albums.
There was a net cartoon a few years ago that had Martha Stewart surviving the collapse of civilisation at Y2K and becoming an impeccably-accesorised barbarian warlord. 
Where’s the fiction in that?
Charles Starkweather and Jim Morrison have unnamed cameos in the long edition of THE STAND.
THE DARK KNIGHT RETURNS (kinda post-Apoc… well-pre-post-Apoc 
) has Reagan STILL as President and The Joker’s first public appearance after his release from Arkham on The David Letterman Show w/ Paul Shaeffer also.
THE CHRIST CLONE TRILOGY has a thinly-disguised Robert Mueller of the UN as
The False Prophet and the AntiChrist preaches a sort of Scientology.
Hey, I was gonna say that! I recognized Heinlein and his wife, but who were the others?
There is a Phil K. Dick short story, I forget the name, set after WW3 and where the dominant religion is Scientology and Elron is deified.
ETA, the name of the story may be The Turning Wheel.
The Philip Jose Farmer story is The Making of Revelation, Part I, and it’s evidently been reprinted several times since that anthology:
I came in to mention Footfall and the Running Man.
In Footfall, the writers included Niven and Pournelle along with the very obvious and revered Bob Anson. I can’t remember the others any more.
Jim
BTW: It was Pink Floyd that had the Cameo in Postman, Geez!
Fatherland (Robert Harris) has Joseph Kennedy as President.