How to decode the output of that free CueCat bar code scanner, which you can get for free from Radio Shack, or order (for cost of shipping) from the CueCat web site. Need more info? See this little Linux driver, which gives more information on the data format in its README file. Picked one up the other day. Guy gave me a dirty look when I didn't want a catalog.

As we can see, it's super easy to write software to use it without installing their default utility (which merely matches barcodes to web pages from their central database). Parse a book's ISBN and bring up the Amazon.com page, to catalog automatically in a database, for example. Better yet, scan your CD collection into a program that uses CDDB to fetch the track titles. (Faster than sticking your entire collection into the drive, anyway, which is what you'd have to do without a scanner.)