Barefoot running has exploded over the last year.  The theory behind this trend is that an unrestricted foot leads to strengthening of small muscles, increased flexibility and prevention of injury. 

Most podiatrists cringe at the thought of barefoot running, as this may lead to trauma (ie. stepping on broken glass, gravel and other debris), stress fractures and tendon/ligament injury.

If you are considering running barefoot or in a minimalist shoe, you MUST start slowly.  An abrupt transition is sure to cause injury. 

Minimalist shoes to cosider include Vibram Five Fingers, Merrell, Saucony and Brooks.

You may also want to read the book Born to Run: A Hidden Tribe, Superathletes, and the Greatest Race the World Has Never Seen by Christopher McDougall.