Actually, I've found 3 mostly good CD Catalogs, but not one *great* one--at least not for Gnome.
What I have found is gnomecatalog, cdcollect, and gwhere.
gnomecatalog is the prettiest and closest to what I want in the end except that it doesn't completely work. I'm using the latest version (0.2.0) from last July. It's hung on MP3's, lost it's cookies over a 5000+ file filled CD, and played the MC with my CD's for minutes upon minutes without so much as a progress bar change.
Then there's the other two. GWhere's similar to gnomecatalog, but without the pretties. CD Collect is about as minimal as you can get and therefore leaves much to be desired.
If anyone out there knows Python, please crunch these three apps together and send me the link to your SourceForge project's page. I'll be delighted and send you cookies. :)