when you have a texture, perhaps a seamless texture, and map it in a spherical projection, you tend to see the pinching or compression at the poles. To avoid those, you can remap the texture through a polar mapping correction.
If you use the GIMP (free), ARtWeaver (free) or Project Dogwaffle (free or commercial versions) you can install a Lua/gluas plugin in each of those and find additional filters available, written in Lua.
I just converted Paul Bourke's generic algorithm for polar transform into such a Lua script. Give it a try if you have an imaging application with Lua support.
http://www.thebest3d.com/dogwaffle/lua/polar
If you know other applications which support Lua, in particular which support the gluas subsystem for scripting new filters, please let me know. Note that not all Lua scripts coming from Project Dogwaffle or ArtWeaver will run on the GIMP, since we also have added a GUI system called the guiserver, and other proprietary elements, but this particular filter uses none of that and does work on GIMP 2.2 with the current gluas plugin (look for it in Filters>Generic>gluas... )
sidenote: I find the execution on Dogwaffle (PD Pro 4) significabtly faster than on GIMP, is it just my version of GIMP/gluas or is it indeed so much more optimized? Anyone else care to compare numbers?