I'm putting together a 650b Jack Taylor touring tandem at the moment. While not exceedingly rare, I'm sure it will not be a commonplace bicycle when I'm finished with it.
I've modified a few accessories into a demultiplicator contraption that I've yet to see anywhere else. Here is a link to view this tandem project via flickr.
Cheers, and Have a Nice Ride!
http://www.flickr.com/photos/3584086...n/photostream/