I have an interest in extended techniques as it relates to the guitar. My doctoral paper, Extended Techniques for the Classical Guitar: A Guide for Composers, was written to be used as a manual for those interested in composing, notating, and/or performing these different techniques for the guitar.
You can download my document here: Extended Techniques for the Classical Guitar
In January, 2010, I composed the piece, Good Night, for classical guitar and soprano which demonstrates some of these techniques. The video below is of the premier performance at Ohio State.
For
example, from 1:36 to 1:56, I bounce a pick on the strings.
From 3:09 to 3:20, I hit the strings on the fret board with both hands.
These two techniques are used to mimic the sound of the wind and rain.
In the poem, a mother is trying to comfort her child who is afraid of
the storm outside.
In addition, I use a slide from 4:34 until the end.
Bouncing the pick on the finger board is one of my favorite techniques. I use this during the opening of Sun Kiss, from 0:21 to 0:34 and again from 0:56 to 1:06.
The guitar sound is sent through an echo patch using Max/MSP. It gives it a little different feeling compared to Good Night.