The helptab extension provides contextual help for CiviCRM: on any back-office CiviCRM page a little tab appears on the right side of your screen. Clicking on that tab will bring up a list of articles related to this page, clicking on the article's title will open it in a new tab.
The articles, or help items, do come from various sources including the User and Administrator Manual, the Wiki, the forum, Stack Exchange, as well as third party sites such as the Cividesk Knowledge Base and CiviTeacher instructional videos. The extension can host any news sources of content - contact Cividesk to add your content to the Helptab!