My actual backup plan is three hard disks: one in computer, two external. The every time I shoot another 4gigs worth of keepers, they go on a dvd. I don’t expect the dvds to last more than a few years. Recent shots stay on memory cards until they can be put on at least 2 of the HDs or an HD and DVD. Really good pictures go to my parent’s computer which has gigs of storage and no one using it. No fancy services, I just copy the files over to the drives, and let md5sum make sure the copy wasn’t corrupt.
I wouldn’t trust a web host that says in the EULA that they aren’t responsible. After all, if you are willing to pay for a backup service, use a backup service. Amazon has S3 which looks rather cheap for it’s guarantees, but I haven’t used it. Just get a couple TB size drives from different companies, and when you take new pictures, put them on all the external drives at the same time. If you want really safe, never reuse a memory card; just treat them like rolls of film.