I like to recommend that everyone buy a copy of Fractal Terrains and a couple of copies for their friends. I admit that statement reeks of self-interest because every copy of FT sold provides me with royalties, but I still like to make that recommendation.

If you're interested in FT, download the demo from the ProFantasy web site. It does everything that the full-featured demo does except that the export resolution is limited. It will indeed render your image as a globe and let you rotate that globe. Just import your image as an image overlay that covers the whole world and use the Orthographic projection (hold down Shift on the pan tool to change the center of projection, which will rotate the globe).

Wilbur will do much the same thing: load the image as a texture; use Surface>>Map Info to set the top to 90, left to -180, right to +180 and bottom to -90; then use Window>>Map Projection with the Orthographic projection to view your world as a globel (click and drag on the image to move it).

Both of these programs will let you look at a globe and both offer some form of editing/generation for "worlds". There are lots of other programs out there. Most folks around here that use FT or Wilbur seem to use them as a starting point for generating eroded light maps and then use that information as the starting point for maps in other programs such as GIMP of Photoshop.