Vestigial organs are structures that have lost all or most of its original function in the course of time, and serve no apparent use.
Vestigial Organs in Whales
"...sometimes bones are present in an organism but are reduced in size and either have no use or have a less important function than they do in other, related organisms. Such structures, which are considered to be evidence of an organism's evolutionary past, are called vestigial structures. For example, the hind limbs of whales are vestigial structures." HOLT BIOLOGY - Holt, Rinehart and Winston, 2006, Pg. 286
This small pouch attached to your large intestine, at the junction of the small intestine, no longer aids in digestion, and none of the 1 in 20 people who have one removed seems to miss it.
Five Useless Body Parts -
Much of the clip art on this site is courtesy of Phillip Martin.