Kananga - when I leave my dogs alone in the house I use a CD on repeat. The CD is called 'Relaxation Music for your Dog'. It is very effective in keeping them calm. I think I got it from Crosskeys. The producers are Omnibus Media and their web address is www.musicsales.com I can also endorse the Dap which I have found effective in calming my dogs when necessary.
Interesting. You know the long drive back I had when I initially picked him up (2 hour drive home) I had classical music playing which really put him into a deep sleep on the car ride. Ever since he's always calm around that same music.
I should give that a try.