A good, simple and practical idea for an analog to digital application using the CueCat barcode scanner: catalog your CD/DVD/book collection. See also the FooCat BarCode (added on 10/23/00, thru MTHology.)
03/30/01 update: :Killing your :Cat — Your :Guide to :Catricide.
04/21/01 update: Getting Product Info on Cue.