Open A Guitar Tuning

Open A guitar Tuning is very usefully in slide playing. What you do is actually tune the guitar to an A chord. Now when you bar all the strings, you are playing the major bar chord for the position you are playing in.

Robert Johnson uses this tuning for Crossroads Blues and Come on in my Kitchen.

Here is a little video of how to tune and play in Open A:

http://www.associatedcontent.com/video/28799/open_a_guitar_tuning_and_crossroad.html
http://www.associatedcontent.com/article/489069/open_a_guitar_tuning_tips.html