I'm trying out the Oboe mp3 locker service from mp3tunes http://mp3tunes.com as I'm working on an mp3tunes/magnatune partnership with mp3tunes CEO Michael Robertson, and I want to get better acquainted with how Oboe works.
I put all of magnatune into my Oboe locker, so that I could access it from iTunes when I'm traveling. I'm in Paris currently, with good quality WIFI in my hotel room, so I'm listening via the iTunes/Oboe plugin. Plus, as we add more albums to Magnatune each month, Oboe picks up the new stuff and uploads just that, which is very handy.
It works really well, with the only problem I've found is that the mp3 genre isn't passed through to iTunes (you can see that in the screen pic above), something they told me they're going to fix. Otherwise, it works like a charm.
Next up for Magnatune/mp3tunes is providing all of magnatune's 128k mp3s through their sideload http://www.sideload.com/ service so that more people can discover magnatune's music.