There is about 3-4 threads in the forum talking about Barcode reader for N8XX. They pretty much all seems to be dead. But the answers are still vague. I am not a programmer or a coder so I have absolutely no idea on how to implement this.
Can we get a 2D/QR Bar-code reader for N900 and other tablets?
Some thing like this
And as I remember other N-Series phones came with the built-in app like this.

Other discussion on the older tablets.
http://talk.maemo.org/showthread.php?t=8836
http://talk.maemo.org/showthread.php?t=33032

That would be really useful!

There's an app called mbarcode in development. There's a thread about it here

There is lot of those moments where you find something on the web while you are using a PC and you want to store that web address on your phone. It would be really convinient to add that by using the code reader, since we can already have an addon on firefox which will automatically generate a barcode to scan for. or you find a image on the internet that you want to make your desktop image but the url is too long.
there are lot of other times that this would come handy and useful.

You can take a shot of the screen using mbarcode and have it decode the barcode. The decoded data is then shown in a text box in mbarcode so you can copy and paste it somewhere if you want.

sounds like already done?!

normaly I would post this
but I think mbarcode, which is already in dev, will cover your problem