IcoFX - IcoFX is an all-in-one solution for icon creation, extraction and editing.
Icon Slate - Icon Slate lets you easily compose, import and export desktop icons in many formats.
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.
FastIcns - DigitalWaters.net Projects - by Matteo Mecucci and Juna Salviati
IconWorkshop - Application to create and manage software icons. A must for developers.
icoworks - .ico editor for Windows 8 and Windows RT