If you believe in having as many strings as possible in your guitar, take a look at the Pikasso, a 42 string guitar made by Linda Manzer for guitarist Pat Metheny.

The Pikasso took 2 years to build and has four necks, two sound holes and is under 1000 lbs pressure when the strings are strung up to high tension. The Pikasso can be heard in a number of tracks by Pat Metheny including "Into the Dream" and also in the video featured below.