This is a service provided by a Pittsford startup, Techrigy, Inc. It allows you to backup your blog including backing up comments and image files in your posts. It also automatically does a daily backup of any changes to your blog. Right now, the program doesn't support custom templates, blog engines, or private blogs, but all public blogs on all major platforms are good to go (blogger, wordpress, livejournal, etc.).
Furthermore, you can restore your blog to the same blog platform, and you can export a copy of the backup to your computer. You don't have to download any software- all you do is create and account and register the blogs you want backed up. You don't have to maintain anything. Of course, you can manage your backups anytime by signing in to your account.
You get 50 MB of space, and the service is free.