For a great overview of available cloud backup solutions, check out the recent AudioTuts+ article: 10 Secure Online Backup Solutions for Pro Audio. Except for Gobbler, the backup services mentioned are for any type of file, not just audio. We have accounts with most of the services mentioned.
Another one of the benefits of these services is that, with your files backed up to the cloud (i.e., the web), you can access them wherever you have an Internet connection. That’s pretty convenient! Carbonite, Box.net and Dropbox, possibly others, also offer mobile apps, making it that much easier to use your files remotely. We have iPad apps for each of these three services.
Incidentally, Box.net is offering a generous 50GB of free storage for life for all iOS users through December 2, 2011. To get your 50GB of storage, just sign up for an account through an iOS device: iPhone, iPad or iPod touch by that date.