The spectacular Jaga Jazzist using it. Though the OP-1's merely one of many other synths. It's sitting next to what looks like an Alesis Micron.
https://www.youtube.com/watch?v=tJPplqqZBqE
Man I love Dan Deacon, this is worth a bump, one of the most incredible and uplifting live performances I have seen:
https://www.youtube.com/watch?v=heFRwLfjVXI
OP-1 used throughout.
I’m not familiar with this band - I randomly came across this watching these AV Club covers. I was like, “where are the synth sounds coming from?? Oh… I see.” 
http://www.avclub.com/video/weather-station-covers-joy-division-225622
I’ve seen Panda Bear with one hooked up while playing live.
I loved this impressive performance when it was released. I wanted to watch it again just now, and just noticed the OP-1. And it seems to be the main synth used. Henrik is using one and Bugge is possibly playing one on the second song.
Bugge Wesseltoft, Henrik Schwarz & Dan Berglund:
Recently discovered Christian Löffler—loving some of his work.
https://twitter.com/chris_loeffler/status/648452131633131520
Blanck Mass, one-half of the Fuck Buttons with Andrew Hung, uses an OP-1, cause Jean Michel Jarre recommended it to him.
Amason with a bunch of OP-1s. (via Reddit)
https://youtu.be/JJEtAZvmQn8?t=62
Nice! I want an Instant Lo-if Junky pedal.
I’m just coming across the OP-1 everywhere lately. (I’m not an OP-1 stalker.)
Giraffage (Charlie Yin) is with it.
Just reposting dsk2600’s post in the Video thread here, for nerdy comprehensiveness.
Flute and Chet Faker.