Amazon is releasing a site called SoundUnwound — a version of IMDB for musicians, editable by anyone like Wikipedia. Few know that IMDB, the movies database, is owned by Amazon.com. But the universal vendor seems to value the data therein — knowing which obscure movies a now-famous actor starred in helps cross-sell DVDs. Most of SoundUnwound's information comes from YouTube, Wikipedia, and MusicBrainz — another open-content music database. You can find out who the sound engineer for Amy Winehouse's studio debut was, if you're so inclined — okay, it's Jimmy Hogarth. With free data, Amazon gets what it pays for, in the form of broken track listings and unknown playtimes on songs, but it's still good enough to help upsell you more MP3s from its struggling music store.