A few months ago I started using Carbonite, an automatic online backup. It’s 5 bucks a month for unlimited data. It’s not perfect, and it has some pitfalls people should know about, but at 5 bucks a month without having to worry about limits I couldn’t pass it up. My full review is here: Carbonite review http://blog.hanfordlemoore.com/2006/11/22/review-carbonite-online-backup
I use CrashPlan (similar to Carbonite but better) and last Labor Day my hard drive crashed. The only backup I had available at the time was CrashPlan as my other backups were not with me). Good thing I was on vacation at a hotel with a big pipe (big bandwidth). I got all 200+GB back in a day and was running again without a hitch.