N-Tune = a tuner built into a volume knob

I've never had a problem tuning guitars. I own a simple £15 tuner and use that. But people love solving the problem, over and over again, whether it's the Korg Pitchjack, or the (now heavily reduced) String Master 'Robotic' Guitar Tuner. Now the N-Tune is a $70 DIY kit to add a tuner with a ring of LEDs which sits underneath the volume knob on your guitar. There's a Fender version and a Gibson version, and they both come with a few coloured rings to match to your guitar. Or you could use a little pedal or whatnot...