I haven't used it for any business purposes, but I do use the Mozy home offsite backup, and it seems to work pretty well.
http://mozy.com/
Thankfully I haven't needed to restore from an online backup, but I have replaced my computer, and migrating from one to the other wasn't too bad. I use it primarily for personal financial files and documents that I care about. The free home service is only 2 or 4GB... They do have a more business oriented service as well.