From MozillaZine Knowledge Base
“What’s Related” was a browsing feature first introduced in Netscape Communicator 4.06, allowing users to retrieve a listing of websites similar to the one currently being viewed. This preference actually dates back from that browser—it never did anything in Mozilla, despite having checkbox in the browser preferences.
Mozilla’s implementation of “What’s Related” is dependent upon the appropriate sidebar being open. It’s not implemented at all in Firefox, Minimo, or Camino.
This preference has had a value set in various default preference files (browser-prefs.js and firefox.js until recently) for quite some time for unknown reasons, resulting in a useless entry in about:config.
Possible values and their effects
This is a boolean preference, but as mentioned previously, neither value has any effect.
Mozilla (Milestone 9–15)
A checkbox labeled “Enable ‘What’s Related’” is located under “Edit → Preferences → Navigator → Smart Browsing → What’s Related”.
First checked in
Present since at least 1999-06-07. Exact checkin date unknown.
Has an effect in