Watch the Open String Technique Review online guitar lesson by Stu Hamm from Stu Hamm U: Solo Bass
Here's a technique that I've got a lot of mileage out of. You can hear it in my playing as far back as the title track and "Country Music" from my debut album "Radio Free Albemuth". Doubling notes creates a unique sound, as you are playing the same note on two different strings. The strings sound slightly different, and you get a nice flanging/doubling effect. From using the open G and playing the G on the 5th fret of the D string, I moved on to playing the open G and bending noted into chord tones on the D String.