Last night I watched a film called Coherence, a sci fi flick you've probably never heard of. Nice ideas and I enjoyed it. Personally I thought it lacked the tightness of some of the others mentioned, mainly in the exposition. Triangle, Primer, Time Crimes, Time Lapse being the pinnacle of that indie conceptual scifi stuff.
I actually reckon The Quiet Earth is a borderline masterpiece. Just about the finest depiction of desolation caught on film.
Watched Coherence myself last night and thought it was quite entertaining, will watch it again as lots going on and missed a few clues.