Panoglview

panoglview is an OpenGL hardware accelerated immersive viewer for equirectangular images, originally created by Fabian Wenzel and currently hosted on the hugin sourceforge site.

The license for panoglview is the GNU General Public License (GPL).

You can download pre-compiled versions of panoglview as part of the hugin installer bundles for OS X and Windows. panoglview is available for linux distributions through the usual channels.