I have been using SpiderOak for my offline back up solution for some time now. The main advantage I have found is that you don't need a separate folder like in Dropbox and the synchronisation feature works really well. So I currently have three computers all sync'ing wonderfully with each other. Anyway, there is now a referral programme and so I thought I would take advantage. If you use this link you get the standard 2GB + another 1GB free for life.
Download SpiderOak Backup and get extra 1GB free
