Remember the days when Metallica were the villains of the digital music world for suing their own fans? Now they’re actually one of the more innovative artists, having grasped the nettle of digital for promotion and retailing, while also showing a more relaxed attitude towards file-sharing.The latest example is Live Metallica, an iPhone app that went live this week. It costs $0.99, and lets fans stream professionally mixed recordings of the band’s concerts as they tour the globe. Well, at any one time, there is one show available for free streaming – the latest one. But the app is really about showcasing the archives from the band’s LiveMetallica website, which has been selling live concert recordings since 2004, and just introduced the option to buy single tracks too.So, the iPhone app lets fans listen to samples from these archives, and then buy them from within the app. They’re instantly available to stream in the app itself, but can also be downloaded from the site to the user’s computer. This is interesting, as it’s one of the few examples of an iPhone music app that’s driving paid downloads from somewhere other than Apple’s iTunes Store. It’s been approved, so presumably Apple is comfortable with the idea.