Mac: Google Chrome 10 came with a new feature that made you hold Command+Q down for a few seconds before Chrome would quit. It's gone now, but if you liked the feature, here's how to get it back.
Many Mac users were frustrated when this feature first came out, since it threw off their "muscle memory" of being able to quickly shut down an app with a simple keystroke. However, quite a few people also liked the feature, since it saved them from losing all their tabs when they accidentally hit Command+Q instead of Command+W, for example.
If you're part of the latter group, you can still enable the feature in Chrome by going to about:flags. Look for the "Confirm to Quit" function and enable it. You should get the message back, and you'll need to hold Command+Q to quit—ensuring that you won't lose all your tabs if you miss the right key every once in a while.
Strangely, I'm only seeing this flag in the stable channel of Chrome (version 10 at the time of this writing). Hopefully they'll throw it in the beta and dev channels soon for all to use. Hit the link to read more.
Confirm to Quit Google Chrome [Mac OS X Hints]