It's no secret scanning on an internal iSight can be a pain in the butt, but a recent user anecdote had me scratching my head, wondering, "does that really work?"
I'm sure you know what a barcode looks like, but sometimes, there's a little mini-barcode that follows the main barcode, which provides no useful information, as far as Delicious Library is concerned.
So, this user said when he covers the mini-barcode, his internal iSight scans the big barcode a lot faster. I think it would make an interesting, if unscientific, experiment, if you internal iSight users out there wouldn't mind giving that a try and reporting on your results.