Ctrl-w, for the uninitiated, is an amazing productivity secret. There's a point where your typing speed is so fast that it's slower to backspace to a typo and fix than it is to just delete the whole word and start over. Ctrl-w deletes the previous word. Open up a terminal and try it now.
That's right, a terminal. In OS X (Mavericks, at least), Ctrl-w only works in terminal, including vim insert mode. Option-delete does the same trick outside of terminal--but who wants 2 ways to delete the previous word?! Don't worry: you can get Ctrl-w everywhere in OS X; here's how.
~/Library/KeyBindings/DefaultKeyBinding.dict to look something like this (you may need to create the folder):
"^w" = "deleteWordBackward:";
Or add the "^w" entry to any existing bindings you already have. Restart any program, and enjoy the blazing speed at which you can now type and correct with Ctrl-w!
Disclosure: I can't take full credit for this tip. I learned it here.