Originally Posted by nixcamic
So fisheye-hemi just projects the image cylindrically and I could use any many free/open source programs that do cylindrical projections to defish images with similar effect? That would be interesting.
Short answer: the open source programs and Fisheye-Hemi produce similar, but not identical, results.
Long answer: Fisheye-Hemi isn't equivalent to the cartographic cylindrical projections (e.g. Mercator or Lambert) offered by panorama-stitching software; the cartographic projections will make your images bulge out at the top and bottom, forcing you to crop out these regions of the source image. Fisheye-Hemi doesn't bulge, so it preserves the top and bottom of your composition. (You lose the corners in any case; there's no free lunch in geometry.
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There are several packages out there worth trying; check out the "how do YOU de-fish" thread for examples. Try several programs, and choose the one that works best with your images and workflow.
(BTW, I'm also salivating over ultrawide rectilinear primes; could be a DA14/2.8, a 20mm-ish lens for film, or the new limited when it comes out.)