"Single-Application Mode" in OS X

When someone linked this article to me, the operative phrase "Single Application Mode" made me think someone had just figured out how to use the Mega Zoom SIMBL plugin. How wrong I was.

So apparently back in the olden days of pre-10.0 OS X, clicking a dock icon would hide all other applications. Command-Tab wouldn't, though, so using a combination of these two behaviors achieves the same functionality as Spaces, but faster and easier to modify on-the-fly. Try it yourself:

defaults write com.apple.dock single-app -bool true 
killall Dock

Viola. I have to say, I'm absolutely loving this mode. Too bad it's not exposed in System Preferences.