Everything that I teach is based around the CAGED system, and this is one subject that I ensure all my students learn thoroughly.
The CAGED system is a system of visualisation based around 5 chord shapes on the guitar fretboard. These 5 chord shapes are movable throughout all keys, and provide us with a great platform for learning as well as an understanding of everything we play on the guitar. Another brilliant feature of the system is the use of musical intervals, which in turn provides us with the ability to notate and visualise musical information for ourselves. If all this sounds a little over your head right now, don't worry about it. Simply put, if you're serious about getting good on the guitar, then a lesson on the CAGED system will be one of the most important guitar lessons you'll ever have.
I have recently created a lesson on the CAGED system which you can access here -
http://www.guitarwithlee.com/lessons/caged/part1/number1.htm