A while ago, the Mozilla developers did some research and related some anecdotes, both of which suggested that web browser users use the Back button rather a lot. So in Firefox 3, they made it bigger than the Forward button. (—except on Linux, where they imitated a native design instead, shrewdly surmising that (A:) we like our applications consistent, and that (B:) our native design is pretty sensible.)
At the same time, they combined the Back drop-down menu (showing pages you've previously visited in this tab in this session) with the Forward drop-down menu (showing pages you've visited in this tab in this session that you've then come away from by going Back).
A couple of years previously, I'd made two Firefox extensions that played around with these menus' appearance & functionality. One removed the drop-down buttons, aiming for a simpler look (and leaving the menus accessible by a right-click); the other turned each entire button into the menu trigger (also providing the simpler look, but working less efficiently without providing any extra capability). The latter was never supported, and when the menus were unified I stopped using (& thus supporting) the former.
A couple of hours ago I was thinking about how Google Chrome manages to reduce all of a web browser's UI into five toolbar buttons & two menus, and thinking about how to do a similar thing with other applications, particularly Firefox. I realised that I tend not to remember which page is one Forward, so when I want to go to any page other than one Back, I usually use the drop-down menu. So I may as well get rid of the Forward button.
—plus the necessary incantation to install it and apply it to the main Firefox window. It may look like arse on Windows & Mac, where the Forward button is visually integrated with the Back & drop-down buttons—I don't know. Don't complain. (Fixes are welcome, though.)
It's licensed under the ISC licence, which reads:
Copyright © 2009, Greg K Nicholson
Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.
The software is provided "as is" and the author disclaims all warranties with regard to this software including all implied warranties of merchantability and fitness. In no event shall the author be liable for any special, direct, indirect, or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action, arising out of or in connection with the use or performance of this software.
It's only a minor simplification. Arguably, those overwhelming menus are a much bigger problem (in every sense). But it's something.