I'm at least temporarily captivated by the new version of lala (next.lala.com). They have on-demand streaming of numerous albums and tracks. The twist is that the first stream of a track is free. To hear a track again, you pay 10 cents for perpetual streaming rights or else buy the MP3 for 89 cents. After registering, it appears you get the first fifty perpetual streams free. Digital Audio Insider also points out you can later upgrade your stream to a download for 79 cents.
I don't yet have a feel for the depth of what's available. If I apply the "Wuorinen test," it looks like just 34 tracks by composer Charles Wuorinen are there (although I already own the four albums that represents).
To also gauge the extent of recordings, I count 31 stream-able Steve Reich albums. This includes the new album with Daniel Variations and Variations for Vibes, Pianos, and Strings.
And speaking of Reich, Melissa Hughes blogs of her upcoming participation in the composer's music at the Ojai Music Festival. I'll make it back there eventually if someone can ever pry me away from the computer...