From LQWiki

Eye candy is a general term for visual effects designed to impress the user that may or may not add significant functionality. Examples include 3D effects, transparency, animation, shadows, etc.

Examples:

• Many effects of KDE, Gnome or other Window Managers
• Compiz

• Some games could be considered eye-candy
  • BzFlag
  • PINGUS

Ear-candy is the same idea applied to audio:

• Voice Synthesis
  • festival
  • Swift