A CueCat with webservices?
Scott Hanselman hacks up some more hardware, this time the CueCat to get more info about the books he is reading onto his blog.
Scott decodes the barcode information, changes the UPC into ISBN, then call Amazon's Web Service via REST and finally wraps everything up into a Live Writer plug-in. From the bookscanning project, he got the algorthim to do the conversion of UPC to ISBN.
One can use this for CDs, video games, or movies with the Amazon API for future enhancements.
You can get a CueCat for cheap on ebay for $3.