Here's a very informal sample of the kinds of things that can be done with the Rokinon 8/2.8 Fisheye. The first shot is as-is, the APS-C equivalent is 12mm which is wide enough to show some fisheye effect. The middle shot was manually corrected in DxO Optics 8 with intensity=82 and respecting the aspect ratio, and the vertical edges were re-aligned in DxO ViewPoint. The last shot is the same as the middle shot but cropped to the maximum rectangular area available.
It is obvious that with some careful composition this lens is going to be very handy for architectural shots. I shot this on purpose off the side to exaggerate the distortion.