Just thought I'd share this: I downloaded a free iPhone App called "ZBar" which scans barcodes. I thought it could least who me the different barcode numbers on the Collectable Minifigure packs. Not only does it do this, but it will TELL you what figure is inside! Try it out (if you have an iPhone, that is. It won't work with an iPod Touch, because it needs the camera to read the barcode)!
By the way, the packs have two barcodes on them. The smaller one without numbers is the one that will tell you what figure is inside.