I have not been to this theatre as of yet, but it does offer an interesting schedule of art films. It is located at the Gwanghwamun subway stop, line 5, exit 6. It has a website: http://www.cinecube.net/
There is a upcoming screening on the week of February 6th of the acclaimed THE DIVING BELL AND THE BUTTERFLY.
The sponge house cinema is also located close by: Go to Chongno 3 (sam) stop (line 1, 3 and 5) and take exit 15. Walk straight until the Burger King and take a left, you'll see the theatre on the left.
The problem with sponge house is that it is hard to find info on-line, although this may just be me. I did check the place out a few months back but they didn't have any schedules to take. I may check it out again soon, since it's close to the cinematheque.