ICO

Make icons with Photoshop CS4, CS5 or CS5.1 64-bit for Windows 64-bit systems.

1) Download
2) Copy file to:
C:Program FilesAdobeAdobe Photoshop CS5.1 (64 Bit)Plug-insFile Formats

Do not copy the file to Program Files (x86)

3) Restart Photoshop if opened. New save option ICO can now be found.