The safety of my collection has been one of my largest concerns as music has made the digital transition. With CDs and vinyl, you may damage or lose one or more albums and unless your entire collection is stolen, it's unlikely that you'll lose access to all of it at once. Digital music is a different matter, however. Unless you've backed up all of your songs to a secondary storage device, one bad electrical storm could separate you from your tunes forever (and remember, backing up means having two copies of each file, not just storing your music on a single portable hard drive by itself). With the push toward cloud (or distributed) computing and storage, new services are cropping up to help us not only back up our music offsite, but which allow us to take our music with us wherever we go.
One service that I've been using for years is mp3tunes.com, to which I pay a monthly subscription fee and in turn receive space online to backup all my music to and the ability to stream it to any computer. New contenders include Google Music (currently in beta testing), iCloud from Apple (coming this fall with their iOS 5 update for iPhone, iPad, and iPod Touch), and Amazon Cloud Drive, which is available now.