THE ROCKETEER was a retro superhero flick with memorable dialogue and the best damn casting imaginable, sure as director Joe Johnston later hit it out of the park with CAPTAIN AMERICA: THE FIRST AVENGER, so this one should’ve been a lock.
Near Dark. One of the greatest vampire movies ever, particularly since they never say the word “vampire.”
“We’re… different.”
I love that movie too… and I hate vampire movies. Bill Paxton delivers one of my favorite movie lines ever, “Well I’ll be god damned, if it isn’t shit-kicker heaven!”
I nominate Into The Furnace. Stellar cast (starting with Christian Bale and Casey Afflec) great writing, stunning photography. Why this movie didn’t sweep the awards is beyond me.
I’d have to add Secondhand Lions, with Robert Duvall, Michael Caine, and Haley Joel Osment. Can’t even remember it from the theater, but I fell in love with it first time I saw it on TV.
And Siskel and Ebert both had it on their best films of the decade lists (Siskel 3, Ebert 2). The title became something of a catch phrase. Still, how many people have actually seen it?
Dammit, that was my choice! 
I LOVE that movie, but I don’t remember seeing any ads for it while it was in theaters, at all.
Fortunately, there’s another movie I can contribute instead – Brit Marling’s Another Earth. It’s a very lovely and moving story about guilt, atonement, and redemption which just so happens to have a science fiction premise. (It reminds me a lot of Ray Bradbury’s science fiction in that way…as does Moon).
My favourite movie ever is “Slaves of New York.” I’ve only met one person in my life who has heard of it other than me.
Joe Dirt
It’s just much better than I expected it to be.
Richard Farnsworth and Jackie Burroughs. Music by The Chieftains. Some absolutely breathtaking photography of the Canadian wilderness. A touching romance between elderly people without making it into a dirty joke. What’s not to love? Yet it never seemed to catch on with anybody and I don’t believe it ever got a proper DVD release.
“My Fellow Americans” with Jack Lemmon and James Garner as two ex-presidents who get into various shenanigans. The two actors are flat out funny, as are the supporting cast. I still guffaw every time I watch it when the two heroes join the Dykes on Bykes motorcycle club.
“The Frisco Kid” with Gene Wilder as a hapless rabbi and Harrison Ford as a venal cowboy who wind up sharing a trip to San Francisco. Wilder is priceless, funny, but utterly charming, with a perfect blend of humor and seriousness. Ford is pretty much Han Solo on a horse, but still carries off this buddy movie nicely.
Jim Jarmusch directs Tom Waits, John Lurie, and Roberto Benigni. Anyone who has ever watched it on my recommendation has thanked me.
ETA: from the trivia:
My standard answer for this is The Iron Giant. It’s timely to mention it now, as it’s getting a limited theater re-release later this year.
I really loved Down By Law when it first came out, and I haven’t seen it since - I’ll have to have a re-watch. 
Heh, I was about to recommend Leon: The Professional as a quirky through-the-cracks masterpiece … but when I looked on IMDb, it’s comfortably in the top 30!
I’d never heard of it until a couple of weeks ago. I guess a lot of other people had, though.
Midnight Run was De Niro’s last great film, but I watch it for Dennis Farina.
Josie and the Pussycats - Surprisingly original satire of pop culture and consumerism.
Mystery Men - Super hero comedy. Great cast and direction.
Sneakers - Suspense thriller about a group of computer hackers. The technology and political background are outdated but the movie still works because of the characters.
The 7 Faces of Dr Lao - Great children’s movie.
I would’ve enjoyed that movie a LOT more if I hadn’t read the book first. The movie is a perfectly entertaining early '60s thing that looks like it was made for television. The book is one of the towering accomplishments of 20th century fantasy fiction.
The Circus of Dr. Lao. Charles Finney. 1935. Read it and savor the insanity.
The Trotsky – a really fun Canadian movie about a high school kid who believes he’s the reincarnation of Leon Trotsky.
Let’s Kill Uncle – Uncle is trying to kill a little kid over an inheritance, but no one believes the kid except another little kid. Together they very logically decided it would be better to kill Uncle first.
A Simple Plan, Billy Bob Thornton, Bill Paxton, Bridget Fonda, Brent Briscoe. An outstanding and tense story about three men in a small town who discover a wrecked plane with a shitload of money on board. Their efforts to keep and hide the loot plays out much like a Coen Brothers film.
[Ice Harvest](John Cusack, Billy Bob Thornton, Oliver Platt, Connie Nielsen, Randy Quaid), another Coen-esque film with John Cusack, Billy Bob Thornton, Oliver Platt, Connie Nielsen, Randy Quaid. A thriller with a humorous twist.
My Dinner with Andre. Everyone quotes Wally Shawn from the Princess Bride, but to see him in his breakout film is just a great character study.
Remo Williams-the Adventure Begins was of course supposed to be the beginning of a franchise, but wasn’t. It still has some great dialogue between Joel Grey as Chun and Fred Ward as Remo.
What may be the greatest title of all time: “Faster Pussycat! Kill! Kill!” isn’t a bad little movie either.
And James Garner starred in “Skin Game” with Lou Gossett, Jr. about a free black man and a white man portraying a slave and his owner in mid-19th century America. Garner “sells” Gossett, who then escapes and the two run the same scam in a different town. It looks like it’d be non-PC because of racism, but Gossett’s got a lot of dignity in the role. A well made comedy satire.