Hand geometry
Hand geometry technology takes 96 measurements of the hand, including the width, height, and length of the fingers; distances between joints; and shapes of the knuckles.

Advantages

• Easy to capture
• Believed to be a highly stable pattern over the adult lifespan
• Not as intrusive as retina and
  

Disadvantages

• The hand geometry is not unique and cannot be used in identification systems
• Use requires some training
• Not sufficiently distinctive for identification over large databases; usually used for verification of a claimed enrollment identity
• System requires a large amount of physical space

More at:
A Prototype Hand Geometry-based Verication System
Hand geometry
Projected Texture for Hand Geometry based Authentication