Peter Jackson's Halo: I watched this go up and go down, almost in real time: I lurk at the one message board Harlan Ellison actually frequents, and regular commenter Josh Olson -- who was Oscar-nominated for the screenplay of A History of Violence -- was hired by Jackson to write the thing. He posted as things almost happened, and continued posting when they, well, stopped happening. I think he was paid, at least, and he had the pleasure of talking movies with Jackson and Fran Walsh, so that's worthwhile, too.
Unbreakable 2: Exactly! As frustrated as I was with Unbreakable, I thought it needed to be part of a longer story, perhaps a trilogy. (I liked Harry Knowles's idea that the third film should be called Broken.) Having the concepts behind comic books play out in a recognizably "real" world and not spinning out into bizarro-world ridiculousness in the process might have been a great discipline exercise for M. Night Shyamalan.
Ghostbusters In Hell: Harold "Egon" Ramis explained the film's concept to Mike Russell once, which was (I thought) wonderfully mad. It's about the only place you can go dramatically after saving the world in the first film. Film composer trivia: George Fenton made a "gentleman's agreement" with Ramis that, should the film get made, he would score it; I remember the proposed film being listed in the "who's scoring what" section of Film Score Monthly magazine back in the mid-'90s. (By the way, about Ghostbusters: when people don't know the work of H.P. Lovecraft, I tell them "Ghostbusters is Lovecraft with a sense of humor." Does that sound right to other people?)
Kevin Smith's Fletch Won: A weirdly perfect concept, I think: Smith has openly acknowledged how Fletch creator Gregory MacDonald influenced him; MacDonald praised Smith's script vociferously; and I could so picture Jason Lee as I.M. Fletcher. (I never knew until now that Chris Rock sought the part, too, and that's its own interesting idea.)
David Fincher's Rendezvous With Rama: This one kind of hurts, speaking as a lifelong Arthur C. Clarke fan. This seemed (to me) a ridiculously fortuitous pairing, Clarke and the director of Seven and Fight Club (and the hugely flawed but emotionally-wrenching-when-it-counts Alien 3); if someone working today could pull off anything like what Kubrick did when working with Clarke's ideas, it'd be Fincher. This was going to be a huge release for Morgan Freeman and Lori McCreary's Revelations Entertainment (the company retains the "In Development" page for Rama here), and there used to be a spiffy website (gone now) that went into quite a lot of detail for a film not yet in production. Clarke once said his goal was to get this film made before he died. He's predicted the future quite well before: let him predict the future again! MAKE THIS!!!!!!
And the Rama film actually might still get made, as news items about Morgan Freeman's continued efforts to produce this have made the 'Net lately. I'm not yet sold on Freeman as the captain in the story, though. It's also not clear if Arthur C. Clarke is actively involved, but I hope so...
Trey Parker and Matt Stone's Dumb and Dumber prequel: Um, what now? I...I have nothing to say.
Megalopolis by Francis Ford Coppola: I repeat, Francis Ford Freakin' Coppola. I've never heard of this until now, and the Megalopolis blurb is hella sketchy, but imagining the director who survived giving us Apocalypse Now making a science fiction epic...that touches me in my special touchy places.
Howard Stern's Fartman: The insanity of Howard Stern. The delicious prospect of moviegoers saying "Two for Fartman, please" over and over. The writer of Under Siege writing what the article speculates was "a 120-page excuse for a series of gratuitous lesbian love scenes." This may have been a train wreck, but it would've been a GLORIOUS train wreck.
Arnold Schwarzenegger and Paul Verhoeven's Crusade: Ultra-R-rated swords-and-blood epic as written by Walon Green, who wrote The Wild Bunch. Dear freakin' God. Another gentleman's-agreement thing happened here, I think: I believe director Paul Verhoeven was going to have Jerry Goldsmith write something musically epic for a score. (I may be wrong: Verhoeven once said that his other frequent composer Basil Poledouris would be well-suited for a film about the Crusades, while speculating that Goldsmith would be better for something more pyschological, like a film about the Marquis deSade. But now that both Goldsmith and Poledouris are in the sucky position of being dead, that's sadly a moot point...)
A Confederacy of Dunces: I'm sorry, but I have to follow the lead of Poppy Z. Brite and say "Oh HELL no!" (Actually Brite, who has helped more than once to clean the gravesite of Dunces author John Kennedy Toole, would use harsher language.) This novel is quite possibly a perfect work of art already, and the film would need to be the comedy-epic Gone With the Wind to do it justice. The tone might be flat-out impossible to translate to film in a way that wouldn't cause riots. And I just can't picture Will Ferrell as Ignatius Reilly (I don't know enough of his work to make more of a judgment than that; this is gut-reaction). Maybe I'll just pretend that the Terry Gilliam version of Neil Gaiman and Terry Pratchett's Good Omens is #1...