I saw this woofer at Parts Express, and couldn't help but think it looked a lot like the old KEF B139s. It occurred to me, after lookng at the parameters, that this could also be a very good driver for building a transmission line subwoofer with.
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=264-838
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=264-838