Still, the first question a lot of people ask about MP3 blogs is if they're legal. The answer is that it's a gray area, and MP3 bloggers tend to work from the principle that it's easier to get forgiveness than permission.
The Fiery Furnaces, the Arcade Fire and M.I.A. all got a big push from the MP3 blog world early on, and that's translated to public curiosity, heavily attended shows and, ultimately, album sales. The Tofu Hut's [John Seroff] says he's effectively "offering free advertising to a select clientele" of 1,200 or 1,300 visitors a day.
MP3 blogs are still a grass-roots phenomenon, and they're done only for love. Nobody's figured out how to get anything but a little prestige from curating one, and most bloggers don't have many ethical quandaries about what they do, since they're not making money from it. It's also possible to start a blog very cheaply, or even for free -- one reason they've multiplied so quickly.