Borders in Cambridge has this, it has every CD in the shop in it as far as I can tell. Only problem is that there appears to be no way to listen to CD2 on double CD sets - only the first CD comes up when you scan it.

Strangely enough, I came up with this idea back in 1990 and even bought some barcode bits to prototype it for showing to record shops - but never got round to it. Then, in about '94, wired showed such a unit in their magazine and I swore a bit. My plan was to auto-update all stations via ISDN overnight, and it was also a cunning way of me getting pre-release copies of every CD ever released

Hugo