I'd recommend the 1980 film Death Watch, with Harvey Keitel, which is about the privacy of death and the death of privacy. It was ahead of its time.
I am not young enough to know everything.
-Oscar Wilde

Saw
Ex Machina
, didn't like it. Poorly acted retread of a very, very tired theme, utterly dull. Gorgeous to look at, but other than that, would not recommend.
Did like
Coherence
.
"Here, with a special report, is a midget in a bikini."

Mulholland Drive- very very wierd and awesome movie

Not sure why, but I watched Nerve the other day and I could see fans of Black Mirror enjoying that movie. It's not sci-fi, but it has the dark, risk-taking element.

Children of Men
Donnie Darko

Demon Seed
(1977) with the divine Julie Christie
.

Strange. I thought Ex Machina was unbelievably tedious.

The Outer Limits (the one done in the 1990's) would be a great show for you fans to watch. It dealt a lot more with technology and its dark implications, more than The Twilight Zone ever did.
My list of 1,400+ wild 'n weird movies:
http://www.imdb.com/list/ls053942167/

Cruel & Unusual
It's on Netflix now.

Snowpiercer
Besides it being a very nice made science fiction movie (that deserves more attention). It has this same sad, smart future tech mixed up with political theme in it.
Dark city
If you thought the Matrix was great, go watch this gem and remind you it came out one year earlier
The signal
I was hoping for the end to be this way, but they never have the guts to pull it of. I was wrong. Instant classic for me.

Not as much sci-fi as Black Mirror but very similar outlook in looking towards the dark side of humanity -
Spain's
Wild Tales (Relatos salvajes)
at
http://www.imdb.com/board/13011894/?ref_=fn_al_tt_1
It's an anthology of shorts in which people set out to take revenge, protect their own selfish interests and of course it all ends up going wrong. Or not, depending how vengeful you are.

Paranoia Agent. I know its an anime but it reminded me a lot of Black Mirror and Mr Robot.

For future reference, you can create links to movies by using the [link=tt#######] markup putting link=tt0070904 inside [square brackets] produces
Welt am Draht (1973)
.
Don't listen to the negative ones; their arguments are irrational.

Definitely "
Lain - Serial Experiments
". It's an anime, but not like any other anime I've ever seen. In my opinion, anyone who likes Black Mirror would love Lain and should at least give it a watch - if they can find it. I think it's 13 25-minute episodes.
Other than that,
Jacob's Ladder
,
Utopia
(the British show) oh, and
World On a Wire
if you can handle sitting through a 3-hour German movie with English subtitles. It's very, very good - well worth your time. Don't be fooled by its "TV-movie" status or that it's from the 70's either - it's all kinds of Twilight Zone-ahead of its time-techno-social-bizarro-sickness. It's on YouTube as well, at least last I checked.
World on a Wire
: http://www.imdb.com/board/10070904/?ref_=nv_sr_1
Enjoy!

I would add-
Enter the Void
www.imdb.com/title/tt1191111
Lost River
www.imdb.com/title/tt2366608
Her
www.imdb.com/title/tt1798709
Ummmm, I'm sure there are more but all of the other replies have some good ones to checkout.
Anyone with any other suggestions?

I would add-
Enter the Void
www.imdb.com/title/tt1191111
Lost River
www.imdb.com/title/tt2366608
Her
www.imdb.com/title/tt1798709
Ummmm, I'm sure there are more but all of the other replies have some good ones to checkout.
Anyone with any other suggestions?

Here are some movies that I think share some aspect of the techno-social themes, darkness, and haunting Twilight Zone tone of Black Mirror. I imagine people who are into this kind of thing have already seen these, but I'll recommend just in case
Safe
: 1995 Todd Haynes movie about a well-to-do woman who develops a sensitivity to various toxins and literally becomes allergic to the modern world.
Timecrimes
: a great, underrated, somewhat dark Spanish film from 2007 I don't want to give away anything, because there are so many twists and turns, but more people should see this!
The Experiment
: 2001 German film inspired by the real-life Stanford Prison Experiment, which studied power and vulnerability. Brutal.
La Cabina (The Telephone Box)
: an eerie 1970s Spanish short film available to view on youtube: https://www.youtube.com/watch?v=bKkfGG9q32c
Videodrome
(Cronenberg): This is classic of weirdness. But hard to explain! It's about media, violence, loss of identity. You just have to see it.
They Live
: Media messages are revealed to be coded commands, brainwashing the human race. A little morefun than Black Mirror but bears some resonance!
Upstream Color
: I had mixed feelings about this, but Black Mirror fans might like it. It's a fragmented narrative about a couple of people who have both undergone a strange ordeals that messed with their memories & identities, then they meet each other and try to put the pieces back together.
Duel
: Very strange, low-budget early Spielberg film about a big-rig truck that starts terrorizing a random driver.
of course most people will have already seen this, but
2001: A Space Odyssey
also comes to mind.

Just adding to what's already been mentioned
eXistenZ

• I think fans of
  Black Mirror
  would appreciate most of Cronenberg's work.
  Darknet
• A Canadian horror anthology series that certainly doesn't match the quality of
  Black Mirror
  but still manages to be solid genre entertainment. There are only 6 episodes, so you don't have to worry about a time commitment.
  I believe both are currently available on Netflix.

Other shows to recommend:
Utopia
(the UK show - not the reality TV program. Just about to be remade in the US by David Fincher for Netflix)
Orphan Black
The Prisoner

• 60s version
  Movies
  A Scanner Darkly
  Moon
  I owe my solitude to other people. ~ Alan Watts

Even though ex machina is well made, the idea is an old thought experiment about AI and there's really not much else and they don't explore it deeply. I thought "the machine" had better ideas, but it's a harder swallow.
But I would recommend anything by Vincenzo Natali. Cube, Splice.

The movie "Gamer" is not exactly Academy Award tier, but 15 Million Merits actually reminded me quite of a bit of its depiction of a hyper-sexualized, soulless society.

I don't know about a movie, but if one hasn't ever seen all of the early Twilight Zone Episodes, that's what I would suggest. As well as the later Twilight Zone episodes, Art Gallery and tales from the crypt.
It mostly reminds me of the early Twilight Zone. Rod Serling would love this show. The second episode, I wished there was a narrated intro for that one, but alas it isn't needed.

What I love about these type of threads that every once in a while I find something that intrigues me to check out. I think that's how I heard of Black Mirror.
Never heard of The 10th Victim and now will have to check that out. Thanx.

"The 10th Victim" (1965) starring Marcello Mastroianni & Ursula Andress. This foreshadows the rise of reality television (and it's ultimate nadir) 4-5 decades before it happened.
It's on DVD (must manually select English language audio; otherwise defaults to subtitles) and Amazon Instant Video. I don't have Netflix, so I can't say.