Sandbox

Is there an extension to allow registered users to rate an article? I don't want comments at the end of each article, but just a numeric rating (was this article useful to you?) would be perfect.

This feature is already built into Joomla. From the administrator page, go to Global Configuration. You'll see the settings to show the article ratings.

D'oh! Gracis

Lol no problem! Try playing around with the settings from the Global Configuration page. You'll see a lot of settings to control not only article ratings but also showing/hiding author name, date posted, date last modified, etc. Good luck!