Backing up your blog is a pretty good idea. Till now, if you blog via Blogger, there's been no good options (the options that exist actually have NO ability to restore, and what good is a backup you can't use?)
Now there is: Blog Backup Online
So far, it seems great. It will also let you backup from 1 blog software and restore into another (in other words, convert your blog).
BS"D - בסיעתא דשמיא