This module provides a block with the text "Was this article helpful? Yes | No". If a user clicks yes, a +1 is recorded. If the user clicks no, a -1 is recorded, and clicking either yes or no will give the user some feedback text via AJAX.
I found a need for something simple like this, but I only found conversations that ended in "it's pretty simple, just create it yourself." Well, this aims to appeal to those that are just looking for a simple thumbs up or thumbs down on the helpfulness of a node.