I swore I linked to this already, but I can't find it, so I'll go ahead and post anyway. There's a fairly interesting look at how Sennheiser's latest HD 800 headphones are made at Crave UK. These cans retail for £1,000 and represent the company's keen attention to detail. I'm not totally fond of the general aesthetics, but the internal design is something to be appreciated.
http://crave.cnet.co.uk/accessories/0,39101000,49301532,00.htm
http://crave.cnet.co.uk/accessories/0,39101000,49301532,00.htm