If you're the sort of person that worries about a server crash taking out any of the digital ephemera you generate, then this should be useful. I would particularly note the WordPress one as being a useful thing to have, if you've got a WordPress blog that's not running off wordpress.com, and you don't have it backed up by any other means. Although if you do have that, I really do recommend paying for Vaultpress. It's superb.