Icon Slate - Icon Slate lets you easily compose, import and export desktop icons in many formats.
Faviconer - Faviconer.com, or favicon generator, is online tool for creating favicon.
RealWorld Icon Editor - Create Windows icons and Mac OS icons from images and 3D models in an integrated icon maker.
ConvertIcon! - Converticon is a simple icon utility.
Icon Editor by RedKetchup - View and edit Windows icons (ICO files) directly from the browser. Create icons in 8-bit, 24-bit, or 32-bit color depth. Extract all the layers of an ICO file as PNG images.
Ordinatore - Those who want to tidy up their Macs will surely love this application.