The CD database on freedb.org can be installed locally so that networks without permanent internet connection can query the cddb. I'd love to see an ebuild for it in portage. Reproducible: Always
FreeDB still has the server code available on that page but the latest version, 1.5.2, was released in July 2006. Compiles on amd64 but I haven't checked it it actually runs. The main question is, is there still user demand for having this added to Portage?