I haven't seen any people that use my tuning method, but I'm sure there are.

1. First I look for a string that's still in tune (almost). It's often the low E (I'll assume it's E for the next steps). Usually only one or two strings sound off when playing a chord, so I settle for the lowest string that isn't dissonant.

2. I play the open E (let's suppose it's the reference) or a simple melody in the key of E (on the same string) to get the key stuck in my head.

6. Then I play the other open strings individually, I detune each one then gradually raise it to the desired scale degree in the key of E. It's just like bending, you stop when you hear the right pitch.

In the key of E:

* A is the fourth
* D the flat 7th
* G the minor 3rd
* and B is the fifth.

If the E string is out of tune compared to the others, I switch to another key (often C) or play an E on another string.

It's a very quick way of tuning ; I don't like tuning with the conventional method (open string vs 5th fret on the string above) because it sounds very unpleasant and it takes more time (at least for me).