Most scanners have a programming interface in which you can not just setup how the scanner works and how the data is formatted, but you can also configure what keystrokes it sends (like Control sequences and extra text such as a URL)
I just grabbed a random programming guide for a random Symbol scanner to use as an example
So, from the Table of Contents, we can configure it to send "Control characters"
What you would need is to set up a global shortcut with Karabiner, Keyboard Maestro or ControllerMate (I personally use this) to launch a browswer with URL and barcode number as the address. You can even program in the Return keypress to go to the website automatically. It may have to be done in with some AppleScripting, depending on the complexity.
You could set it up so it sends a CtrlB, wait to allow your browser to loaunch and then and the text