img2icns – The easiest way to convert images to icns files

img2icns is a very simple, powerful utility. Just drag-and-drop an image; jpg, gif, tiff, and png files; to the img2icns dock icon and it converts the image directly into a full icns file. You can now use this icon file to change the icon of an application, folder, etc. This little application is the best and simplest way to converting an image into an icon.

See img2icns Screenshot