Here's a link to a photo of another innovative 2-string bass.
http://www.drangers.ca/promo2_high_res.jpg
This is called a "Muckbucket", and although the photo doesn't show it very well, the bucket is a plastic tub (maybe 15 inches?). I suppose the washtub idea isn't new, but this takes it to a new level.
The D-Rangers also feature the Saw (always a big hit).