One of the cool ways is by reading the bar code on your CD, DVD, book, whatever (I guess) with your webcam..or at least the iSight camera, which I'm lucky enough to have. Once it reads the bar code, it goes out to some internet-based information source to pull in info like cover art, track names, title and adds it to your library. Less cool and more time consuming ways include manual entry...ugh.
Being able to hold the bar code up to the camera just right to get it recognized by the camera took more than a few tries, but 20 minutes tops to figure it out, but after that, it sailed. And the look up to wherever it's getting it's information (Amazon?) worked well...when the data was there.
But in over 50 percent of the cases where I had a bar-code I could read (promo CDs sometimes have the bar code purposely obscured...another part of the problem), there was no info to be obtained about it. I'm sure more checking could determine why this is, but it's definitely a problem that should be remedied: A central single place where information like this can be registered by artists or others putting out product. CDDB, for instance, has some of this information and I know for a fact that two of the CDs that Delicious couldn't find information for looked up just fine when iTunes looked it up on CDDB. Could Delicious use that as a source?
Quick wrap-up is that this idea of bar-code reading CDs to indicate which is being used is pretty right on, although actually doing it through the CD player would be more timely. But it all depends on the source for the data and if it's incomplete, being quick on the scan is all for naught. This is worth pursuing for me and TNJT listeners.