The physician has a rewind button and can review the colon more than once.

CNN: Are colonoscopies really necessary for people over 50?

On Amazon.com, for example, book reviewers get rated by other shoppers, who can click a button describing whether a review was "helpful" or not.

FORBES: Magazine Article

On Amazon.com (nasdaq: AMZN - news - people ), for example, book reviewers get rated by other shoppers, who can click a button describing whether a review was "helpful" or not.

FORBES: The Best Of The Digital Download

And we're just getting started -- the button is capable of plenty more, and we'll discuss its many new talents later in the review.

ENGADGET: Samsung Galaxy Note II review Mobile