I love a lot of Balkan/Middle eastern sort of stuff, and it is kind of hard to find really good collections-- a lot of people really like Le Mystere Des Voix Bulgares, which is the Bulgarian Women's Chorus, which is available on Nonesuch--. Another wonderful album, with songs that are probably easier to learn, is Songs of a Russian Gypsy, by Theodore Bikel.I am not sure if it has been released on CD, but it is one of the classic albums. If you learn every song(and you will probably want to), you will have learned most of the basic repertoire of Russian Folksongs, and, surprisingly, many songs that are very familiar--

On a completely different front, there are two CDs on EMI, Paris at Night and Paris After Dark, that are collections of original recordings of many of the best and most popular French Cabaret Songs, performed by the artists who made them popular--not, perhaps, technically folk music, but then again, the melodies tend to be simple and singable, the music ensembles have a traditional sound, and the songs will last forever--

Of my many "International" albums, these are four that I never tire of hearing--

By the way, I have that National Geographic Greece album, and it has some great stuff on it!!