Firefox 16 Beta may not be bursting with new features, but it should at least be a better platform for games. Developers though may be more interested in yet another addition to the ever expanding set of Web Developer Tools Mozilla keeps cramming into Firefox.
The new Developer Toolbar isn't the web developer's alternative to the always popular Yahoo Toolbar, it's actually more akin to a command line for Firefox, though it does come with shortcut buttons to the Web Console, the Inspector and the Debugger.
It's not a true command line though, the emphasis is on making it easier to do stuff using just the keyboard. In this respect it's very similar to the recently introduced HUD in Ubuntu.
The HUD though only enables you to quickly search through the various menu options of a piece of software. Firefox's developer toolbar does that, but it also comes with a couple of new capabilities.
One example is the ability to take a screenshot of the current tab, either of just what's visible or of the entire web page, by typing in something like "screenshot screen.png 3 true" where screen.png is the name of the file where you'll save the screenshot, '3' is the delay until the screenshot is captured and 'true' is for whether you want the entire page or not.
The screenshot tool is actually quite advanced, as you can have it capture just a single CSS selector.
There's plenty of more functionality, especially useful to developers, hence the name. The entire idea is to make it less necessary to use the mouse, dive into menus or click on buttons to do stuff.
If there's one thing developers love is using their keyboard and for good reason too, not having to go back and forth between the mouse or even worse the trackpad and the keyboard saves a lot of time.
Obviously, the developer toolbar is available via a keyboard shortcut, shift+F2 by default, but you can change it to whatever you want, say '~' for example.
There's a lot of functionality packed into the developer toolbar, this Hacks.Mozilla article and the video below highlight some of the most interesting.