There have forever been two ways to quickly get rid of a window in OS X. One, you can hide the window (the fastest way to do this being the key combo of Command + H) which simply vanishes the window until you activate the app again. Two, you can minimize a window (the fastest way to do this being the key combo of Command + M) which sends it into the dock.
Minimizing is not as fast as just hiding the window, as you have to wait for the animation to finish before you can get back to what you were doing. The Mac defaults to an animation called "Genie", but by heading into System Preferences, Dock, and changing the setting for "Minimize windows using…" you can change the animation to "Scale".
It's far faster — almost instantaneous. This way you can minimize (and un-minimize) with (almost) all the speed of hiding, but still be able to see all of your windows in you dock. Plus, hiding a window forces you to hide all of that app's windows, something that minimizing does not.
(For both hiding and minimizing, there is no single keystroke to bring an app back. You have to actually activate the app to get its windows back. The way around this is to simply set a hotkey for your most-used apps in Alfred, or your application launcher of choice.)
I fancy myself more a proponent of minimizing than of hiding — I like to see all of my windows in the dock. What about you?