Places to buy or listen to world music:

Public Radio Market - music highlighted in various programs including World Cafe

Microfondo - Calabash Music - World music, including a free daily download

Smithsonian Global Sound for Libraries - can listen to individual tracks and create playlists

Smithsonian Folkways (search by World, World History is mostly speeches)

Harmonia Mundi World Music Store (also classical)

National Geographic Store Music CDs

Amazon.com's World Music Site, including new released

Metropolitan Museum of Art Store Music CDs

PRI's the World - Downloadable clip on Global Hits

Not exactly world music, but the last 18 years (and various weeks) in Rap! by Flocabulary also some world history songs