Rudi Grobler demonstrates a simple way with which you can have full barcode support in your WP7 application.
Source: Rudi Grobler in the Cloud
Barcode scanning doesn’t have loads of practical use on a desktop (besides point-of-sale terminals) but on a mobile device it’s a whole new ball game! Imagine a word where you can pick up an item, scan it with your phone and it gets delivered to your door… there are loads of scenarios where barcode scanning on you device makes sense! How difficult is it to do barcode scanning on a Windows Phone 7 device?