Carbonite, an online backup service, is now available for the Mac. The service is priced at $55 per machine per year. A free trial is available.
They are even using a Mac on their home page, but it must be an Intel-based Mac running Mac OS X 10.4 or later in order to use the service. Carbonite provides unlimited storage capabilities and automation to simplify your backup needs, with the software running in the background, finding new and changed files and backing them up. Well, as long as you are connected to the Internet. Seems pretty adaptable and they offer a free trial (15 days to try it and if you sign up you get two months free).
I see from some posts that it doesn't yet support external drives, and it doesn't work reliably on Safari. They suggest switching to Firefox if you have a problem using Safari and that appears to fix the problem. I don't have much use for it since I have a Drobo, but the price isn't too bad. If I think I might need to have off site storage someday, I may consider it. Anyone out there use this type of service?