I just applied the Polar Coordinates distortion technique (discussed in this month’s Practical Photography magazine) to a panorama I took during the summer in the Isles of Scilly. Basically, you rotate a neatly stitched panorama through 180 degrees, then stretch it to make it square and apply “distort: polar coordinates”. A little bit of cloning to fill the corners with sky and then more cloning to “fix” the join. I added a solar flare to make it more planetary.
This was the original photo (scaled down for the blog post)