The Mac application icons are truly unique. Icons for folder are plain blue in color also display a small extra design on the folders icon that can help users to identify generally what  that certain folder contains.

Aside from the default icon designs for Mac you can otherwise change these icons of your choice.

See the given instructions below on how to change your Mac icons.

To alter a particular Mac item’s icon to a different one:

• Choose the volume, application, folder, or file in whose icon you wish to stamp onto another, simply click the icon to pick it.
• In the File menu, select Get Info or press Command-I to open the Info window.
• Click on the icon within the upper-left part from the Info window to pick it.
• Through the Edit menu, select Copy or press Command-C.
• Simply select the volume, application, folder, or file in whose icon you intend to change.
• On the File menu, select Get Info or press Command-I.
• Click on the icon within the upper-left corner.
• Within the Edit menu, select Paste or press Command-Vto be able to change the particular icon.
  

  image from panic.com

Change your Mac user account icon

Your current user account has a picture icon in which shows up whenever you log in, (in the event your Mac computer isn’t actually set to instantly log you in), as the standard icon in iChat, also in your Address Book card. When you initially setup your Mac, you possessed the chance to choose a photo for your icon. If you are seeking a change, here is how you can pick a different image.

• Ensure that you are logged into your user account in whose image you wish to change. In the Apple menu, select System Preferences.
• Click on Accounts.
• Click on the Picture tab.
• Click Edit.
• Retarding force just about any picture file in your desktop or perhaps a Finder window into the resulting Images window.
• Make use of the slider in the bottom from the window in order to zoom in in your image. You can even drag the image around from the window to modify the framing.
• Once contented, just click Set to create the alteration.

Otherwise if you want to look for more cool design icons for your Mac you can check these sites, Pixelgirl Presents, The Iconfactory, InterfaceLIFT.