An app called ZBar is the best I have found. Most of the apps make it easy to buy the books on Amazon... not what you want.
One of our librarians is interested in taking her book inventory with her iPad. Are any of your librarians using ipads to do this? She purchased a connector that allows her to connect her barcode scanner through a USB port to her iPad, but we haven't had any luck with it yet.
Technology Integration Specialist
Hartford School District