I know this is an old thread, so I hope it is all right for me to resurrect it.  The concept of guitar noise is something that I find really interesting.  I have played the guitar for a long time, and have been wanting to explore some more experimental sides of the instrument.
I assume that feedback from a guitar into an amp would count, and that has been fun to mess with.  I have also seen some people put various objects through the strings to pin them together, stretch them and so forth.  I really like the sound of a pick put through the lower strings - tapping it sounds like a gong!
Are there any new noise projects that make good use of a guitar?  Any suggestions for new things to try?