SkyViewer is an OpenGL-based program to display HEALPix-based sky maps from FITS format files. The program will display sky maps on a 3D sphere or a 2D Mollweide projection. Real time panning and zooming are supported, as are rotations of the 3D sphere (if you have a fast graphics card). The program was developed and tested in a Red Hat Linux environment, but it should also build under Windows and Max OSX.