GComb
GComb is a gCode viewing tool with an interior focus
... Skeinforge 50-generated GCode files. The jar file in the package was compiled for use by Java versions 1.5 and greator but, its compatibility on different operating systems and utility for different printers and slicers than those it was written for is not assured. However, we coders did our best to make sure that our implementation would not depend on comments in GCode or slicer-specific details, so it should work given files generated by Slic3r and others as well as Skeinforge.