Secure offsite datacenter backups are not a cheap thing, but they're also the only form of backup that you can use that will ensure data integrity during a catastrophic event at the primary computer location... so if it's data you really really care about and there's a lot of it, you're kind of pinned in a corner on options.
I've noticed a couple people have mentioned Mozy. They might be better than Carbonite (doesn't take much), but I'm still not a fan of Mozy for an assortment of reasons: price, options, security methodology...
If you're going to pay someone huge wads of money to do secure offsite data backups, use an option that can potentially work with products like a
Synology NAS with a
little effort, is the only major backup solution that supports Mac, Windows, Linux and Solaris (making homebrew NAS solutions easily supported), has a cheapskate free user option for backing up between friends, offers end-to-end Blowfish encryption and provides you an option to
not let them manage the keys, provides physical hard drive back-up and restoration shipping options for larger data archive sets, is trusted by some of the largest names in IT, industry and commerce, banking, higher education, and scientific research centers, has a strong privacy policy with SAS 70 compliance, and does it all at competitive prices. That option is
CrashPlan.
I've seen, encountered and used a lot of off-site backup storage options with various clients over the years, and the consequences of failure, complexity and security for these folks. For the past couple years, the only pay-to-use outfit I feel comfortable recommending anymore is CrashPlan. I personally don't use anything more than an in-house NAS for the "rather not lose", Dropbox for the "non-secure can't afford to lose for clients", and
SpiderOak for the "can't afford to lose and need to keep secure", and as such, I don't spend a single dime on archival outside of the initial hardware investment and the electricity to run the NAS. That said, beyond just clients, I have personally dog-fooded CrashPlan's free service for a few months and quite liked it for what it was. If I was put in a situation that required paying for data backups though, I'd definitely use it without a second thought... and I don't just say that because I'm a desktop Linux user.
Take the info for what it's worth.