The IntelliScanner mini is a tiny barcode reader that fits on a keychain.The device includes a USB connector for uploading the data to your computer.
It's a little pricey at $US299, but does come with a suite of software for cataloguing such things as CDs, DVDs, books, your wine collection, assets and grocery price comparison.
I could probably use one of these for cataloguing all my maths and Ruby books!
