I used to take guitar lessons as a kid and my instructor would tune the guitar every time I went in using a tuning fork and his ear. Things are a lot simpler now with high tech tuners like the new Intellitouch CT1 Capo tuner from OnBoard Research. The turner clips to the guitar and will work with 6-string and 12-string guitars.
The tuner uses vibration-based tuning technology with a single action capo. The thing is automatic and shows the measures note on a large backlit LCD for easy tuning. The backlighting on the screen changes from red to green when the note is correctly tuned.
The tuner can be put on any fret on the guitar and can be put on the headstock when the capo function isn't needed. The device is made from aluminum and uses a CR2032 battery. Users can also change the A-Reference from 430Hz to 450Hz if wanted and the tuner will shut off automatically after 3-minutes of inactivity. The CT1 sells for $54.95.