When you have that brilliant stroke of genius, you want to write it down as soon as possible. When opening your note-taking app seems too slow, you can actually use Google's Voice Actions to "jot" something down instantaneously.
I never loved voice search, but if there's one thing I'd use it for, it's making quick notes or reminders. Google actually has this built right into Voice Actions. Just start up Google Now and say something like:
Note to self: get milk, eggs, and bread
By default, the "note to self" action sends you an email with your transcribed note in the body, but if you have Evernote or Catch installed, you'll get the option to put the transcription in your note-taking app of choice instead! It's insanely fast, so you can jot down your note and get back to whatever you were doing.