by Axialis Software Use the industry standard to make, edit, convert icons for Windows, MacOS and Toolbars. It supports all formats up to Windows 8 and Lion (OSX 10.8). Hundreds of features permit to produce high quality icons using a professional tool.
by Kristanix Software Convert between image formats from the Windows shell. Supports JPG, BMP, PNG, GIF, ICON, and several other file formats. Also can rotate/resize images. Right click on a file or a group of files in Windows, and select Convert to. As simple as that.