Chungmuro on lines 3 and 4. Has an insanely vibrant film scene, and Chungmuro is the heart of it -- camera shops, film stores/development (color is same day, B&W is next day).
When are you gonna be here? I'll be here for the next two weeks or so and then off for 2 weeks of vacation before a final week here and then back to DC for more edumacation. Lived here for 5 years and am just back for a summer internship.