I have thought about it as well. I got as far as a bit of searching for sources of ISBN data[1]. It looks like the only place in the US to get it is from the en

I have thought about it as well. I got as far as a bit of searching for sources of ISBN data[1]. It looks like the only place in the US to get it is from the entity that manages the US ISBN database -- R.R Bowker[1]. [1]: It seemed an ISBN stream was the best input to act upon at the time -- Amazon API might be another useful source, but then you would be beholden to a vendor's api requirements/restrictions. [2]: http://www.bowker.com/en-US/products/servdatalic_license.shtml http://www.bowker.com/en-US/products/servdatalic_license.sht...