Has anyone but me seen Mambo Italiano?
A movie that’s up for Best Picture this season? That you provided an imdb.com link that has 120,000+ reviews?
I’ll go with The Lost Skeleton of Cadavra, a cheesy reimagining of the 50s B-Movie genre.
Equilibrium
Cadillac Records – Nice biopic about Murray Chess of Chess records about the birth of Rock and Roll
The Wild Parrots of Telegraph Hill – one of the best documentaries ever.
Cashback – Charming (and sexy) slice of life.
Baptists at Our Barbecue – offbeat film about Baptists vs. Mormons.
Amazing Grace – Historical film about the efforts to end the slave trade.
Hoodwinked – Funny animated film
Ella Enchanted – One of the best fairy tale films made (next to The Princess Bride)
I couldn’t disagree more. That movie knocked me on my ass. It’s a great coming of age story with a twist that turns the whole movie on its ear. Worth watching twice. It’s a totally different movie the second time.
Travellers and Magicians, a lovely movie from Bhutan.
I saw this shortly after it came out and loved it. The three leads are fantastic, and I was already a Patricia Clarkson fan. I’ve been falling in love with Bobby Cannavale lately because he’s so cool, and Peter Dinklage is fabulous.
The first moon landing as told from the perspective of the tracking station in Australia that relayed the “One small step…” speech to Nasa and the rest of the world. A lovely, amusing, heartwarming film.
Moolaade - a fantastic movie about female circumcision (wait, where are you all going?!) in Burkina Faso. It’s not an “issues movie” - it’s just a great movie.
The Man From Earth - The goodbye party for Professor John Oldman becomes an interrogation after he tries to convince his colleagues he is an immortal who has walked the earth for 14,000 years. Absurd and thought provoking at the same time.
King of Kong - Oddly compelling documentary about Steve Wiebe’s attempt to break Billy Mitchell’s Donkey Kong record.
King of California - Michael Douglas plays a bipolar father who sets out on a quest to find ancient Spanish gold buried somewhere in LA.
11:14 - The events leading up to an 11:14 PM car crash, from five very different perspectives.
Kissing Jessica Stein - A single girl (Jessica) realizes she might be gay after she makes friends with Helen, whom she thinks is gay.
Bottle Shock - Fictional movie about the 1976 wine competition pitting the best French against the best American wines.
Beer Wars - Documentary about the difficulties microbreweries face going up against the big 3.
These are fairly obscure films that I’ve rated 8 or higher at IMDb.
The Diving Bell and the Butterfly
Inside I’m Dancing (aka Rory O’Shea Was Here)
I’d like to second some of the other posters’ recommendations:
Before The Devil Knows You’re Dead
I thought this was way more mainstream than its 34k ratings would suggest. It’s friggin’ awesome.
Dummy
If you have trouble watching socially awkward people being socially awkward – eg: The Office – this is a tough sit. But it is quite good.
Before Sunrise and Before Sunset
Great double feature. The first is the better one, and it’s from the 90s, but both are definitely worth watching if you haven’t seen them. Because of the way they were made – 10 years apart by the same principles – it’s almost better to let a month or two go by after watching Sunrise before you watch Sunset.
Lars and the Real Girl
This is better than All the Real Girls, but I just like the latter better. A good double feature if you like Paul Schneider. (I’d recommend watching “All” before “Lars and”.)
The Baxter
As a big fan of most of the cast, I was excited to see this. For some reason it just didn’t grab me and I gave up after around 20-30 minutes. I don’t remember why, so it could have been real-world reasons not related to the movie. (Maybe I was sick or something?) I’d suggest giving it a shot just based on the strength of the cast.
King of California
Love this movie, but I’m a huge Evan Rachel Wood fan so I could be biased.
11:14
This is a fun one. One of those “multiple story arcs intersect” type films ala Robert Altman. Not that this is on the level of an Altman film, but it’s still pretty good.
Kissing Jessica Stein
I love this movie. You could pair it with Imagine Me & You to have a lesbian (bi-curious, really) rom-com double feature.
Pieces of April
Dysfunctional family life, another of my favorite genres. Katie Holmes from before she became a Scientology zombie. Bonus points for having Alison Pill, who played the cancer girl on the second season of In Treatment.
I have tons of recommendations, but right now the one I’m in the mood to talk about is Assayas’s Clean. It’s the story of the wife of a recently-deceased rock star, trying to live a decent-enough life that she’ll be able to see her kid again and generally make amends with her past. Brilliant performances and as well-made and poignant as most Assayas films are.
11:14
Thirded. The trailer is pretty good and the actual movie is actually better than you’d expect. Plus, for those with purient interests, Rachael Leigh Cook has never looked hotter.
Dance of the Dead
Zombies take over the prom and its awesome.
Trick r Treat
Halloween-set intersecting anthology movie that is a lot of fun.
How to Rob a Bank
A bank robber and a fake bank robber get locked in a vault and make a funny thriller. Plus, I think Nick Stahl is a great actor (T3 haters can kiss my ass).
The Signal
Stephen King’s Cell but without the weirdo zombie twist.
Slither
Nathan Fillion versus space worms. Probably the most well known movie on my list.
Series 7: The Contenders
Reality TV satire where people hunt each other across the US with guns. Last one standing doesn’t get shot by the producers. Sadly out of print.
Confessions of a Dangerous Mind
Almost completely forgetton directorial debut of George Clooney about the “life” of Chuck Barris.
Frailty
One of the greatest horror movies I have ever seen about a father who convinces his young sons to kill people because they have demons inside them.
How well known is The Bank Job? It was pretty good too. Black Dynamite looks funny, but I haven’t seen it.
Oh, I loved Frailty. I’d also recommend Traveller (came out in 1997) for an awesome Bill Paxton double feature.
Great suggestions! Quite a few I haven’t seen 
My own suggestion is the 2009 film Thirst by Chan-Wook Park (Sympathy for Lady Vengeance, Oldboy).
A priest becomes a vampire in a failed medical experiment, then a repressed young woman in an abusive marriage falls in love with him. He doesn’t like being a vampire, she thinks it’s incredibly cool.
There are a lot of slurping noises.