IcoFX - IcoFX is an all-in-one solution for icon creation, extraction and editing.
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
RealWorld Icon Editor - Create Windows icons and Mac OS icons from images and 3D models in an integrated icon maker.
Sketch - Professional digital design for Mac.
IconLover - Icon editor for Windows.
Adobe Illustrator - Adobe Illustrator is a vector graphics editor.