This is going to open up a right old can of worms, isn't it?
Mine is the Thurston Moore / Marco Fusinato collaboration "TM/MF", which was the "soundtrack" to an art installation where Thurston improvised ten one-minute tracks (shoving the guitar against an amp, laying it on the floor, sliding a bottle along the strings), while Fusinato used the "music" as inspiration for ten paintings, each created usng a different medium, within the length of time that the track played.
Each of the ten paintings, so far as I can remember, consisted of a large red square. Each of Thurston's improvisations consisted of a fucking racket. I think you probably had to be there.
http://www.physicsroom.org.nz/log/archive/12/rhodes/