As does middle-click, which is super-handy.

Sometimes Ctrl+w can lead to horrible pain if you accidentally hit Q which is just next to w.

Chrome has a menu item toggle called "Warn before quitting" that I just enabled, and it has already saved me a bunch of times!!!! In OSX it's under the Chrome menu item (before File), don't know where they stuck it in Windows.

I can't seem to find this in my settings : (. This bit me every once in a while, and as I keep hundreds of tabs open, it's a huge pain in the ass to restore Chrome. I ended up remapping the ctrl+q shortcut to do nothing.

I don't think Windows has it, also because the keyboard command to exit an application is alt+f4, which isn't easy to hit on accident.

On Mac OS X at least, you can just remap Command-Q to something that's harder to press by mistake in System Preferences > Keyboard > Shortcuts

This is pretty horrible but fortunately easy to fix. I use an extension called disable ctrl q or similar.

Restart Firefox, then choose History/Restore previous session.

BetterTouchTool: map 4 finger swipe up to cmd+w.