I've been wondering when the 'skip to top' functionality that is now a staple in so many iOS apps would appear on OS X. It seems to be here now, albeit in a limited fashion. As such, this hint only seems valid for Firefox.
In order to skip to the top or bottom of a web page, simply swipe up or down on your trackpad using three fingers.
[kirkmc adds: Yes, this works in Firefox, and in Opera, it moves about 4/5 of a screen.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20120803142100796