An icosahedron-based method for pixelizing the celestial sphere
  For power spectrum estimation   it's important that the pixelization   of a CMB sky map be   smooth and regular to high degree.   With this criterion in mind   the ``COBE sky cube" was defined.   This paper has as central theme   to further improve on this elegant scheme   which uses a cube as projective base   -- here an icosahedron is used in its place.   Although the sky cube is excellent,   a further reduction of 20 percent   of the number of pixels can be obtained   while the pixel distance is maintained,   and without any degradation   of accuracy for integration.   The pixels are rounder in this scheme, where   they are hexagonal rather than square,   and the faces are small in this implementation   which simplifies area-equalization.   The reason distortion is lessened is that   the faces are smaller and therefore more flat.   To use the method, you can get   a FORTRAN code from the Internet. 
Max Tegmark (IAS)