Just think about this for a moment: somewhere out there, a bunch of 1s and 0s are floating around in a server - specks of plankton in an unimaginably infinite ocean of data - and this is what they sing when they come together:
"OK Google, remind me to buy some nappies and milk after work"
We hear voices
It's no secret that Google Now uses the ethereal power of the cloud to process your voice commands, but you probably didn't realise that all those commands, uttered in your voice, are stored online. And you have the power to access them all.
Before you grab the pitchforks and the 'PRIVACY BREACHED' picket signs, it's worth noting that you have to be logged into your own Google account to access the Audio History list, so you're (reasonably) safe from the prying eyes of the KGB, MI6 and NSA - none of whom are likely to take an interest in your 2am voice searches for industrial-sized bottles of Sriracha sauce.
Google states that "Voice & Audio Activity helps recognize your voice and improve speech recognition", which is why every seemingly insignificant phrase you've whispered into your phone's ear is nestled in the cloud.
You can of course choose to delete your entire voice history and stop voice data collection if you want to. Just hit the settings icon on the top right, and select 'pause' on the next screen. You'll be hit with a warning saying that voice recognition accuracy may suffer, but you can always enable it again whenever you fancy.
Location, location, location
While we're here, it's worth noting that you can view and/or delete your Location History too, which is also stored in Google's ginormous data boxes. Head on over here to see a map of all your movements (assuming you've had location services switched on), and select 'delete all history' on the left hand side.
Hit the settings button on the top right and, as before, you can opt to pause location history. It's worth bearing in mind however that Google Now services - like local weather and travel information - may suffer.