It’s not my kind of music, but a pretty huge collection of rare Latin-American records is now available online. The collection features lots of artwork and metadata. You can find the collection here, and there’s an article about it with more detail here (it’s also written in English, while the catalogue only seems to be available in Spanish).
It’s a shame that all this info would have to be imported into MusicBrainz by hand though. I hope that in the future there will also be similar projects with MusicBrainz integration (perhaps that project with the French radio that @loujin et al are working on). See also this thread.