Creating an .ico file with multiple sizes - web application
You could try with ConvertICO.
This is a batch png to icon converter which allows to create up to 20 multiple-size icons from images in png format at a time.
You can select as many output sizes as you need.
Another option is IcoConverter.
IcoConverter takes any image and converts it to an ICO pack.
The aspect ratio is not preserved, so squarish images are recommended.